Based on my past experience,  an enrolled device will in general not get stuck in reboot loop because its MobiControl server is not on-line any more.  

My wild guess of the most likely cause is incompatibility between your device agent and the device firmware, which might be automatically updated over-the-air from your tablet vendor support site.

What is the brand and model of your tablet?  Do you remember what MDM policies was deployed to it in the past?  Let's assume you consider factory resetting the device is an acceptable option, and your tablet is an Android device.  Depending on the device brand/model and the MDM policies previously deployed,  you might be able to break the reset loop with any one of the following ways:

1. Boot the device to recovery menu and select "factory reset".

2. Boot the device into safe mode, and see if you can uninstall Mobicontrol from the application manager tab or initiate factory reset in the device "Settings".

3. Boot the device and force it to USB ADB debug mode.  Use relevant adb shell commands to factory reset the device or uninstall Mobicontrol.

Good luck.

Hi Chris, 

Raymond brought up some creative solutions to an Android device that is stuck in a reboot loop with lockdown, I would try them.  

What version of MobiControl agent is on the device and MobiControl server was/is it enrolled in?  In your opinion does the device connect long enough to connect to it's WIFI or Cellular connection?  Lastly, it wasn't clear if the environment it was enrolled in is still in existence, please provide clarification.

Regards, 

1. Boot the device to recovery menu and select "factory reset".

 This didn't work as I have factory reset blocked in the profile attached to the device.  When I select factory reset from the recovery menu, I get the "MDM does not allow factory reset" message.

2. Boot the device into safe mode, and see if you can uninstall Mobicontrol from the application manager tab or initiate factory reset in the device "Settings".

I can't seem to get it to boot into safe mode.  I am holding the power button until the device starts, and then holding the volume down button until Safe Mode appears, but it never does.  The tablet hangs at the AT&T logo and never completes the boot cycle.

3. Boot the device and force it to USB ADB debug mode.  Use relevant adb shell commands to factory reset the device or uninstall Mobicontrol.

I'm working on setting up my environment for this now.  I will provide results once it's ready.

This is on a Samsung Tab E device.  The device is not connected to a WiFi network and I have removed the SIM so cell is not available.  I wouldn't think having an instance that is no longer online would cause an issue like this as essentially it's the same as a device not having an Internet connection where it just can't reach the server.

I'm trying the adb commands now.  I first tried to remove MobiControl, but that gets an error based on the profile policy as well.

adb uninstall net.soti.mobicontrol.elm.samsung
Failure [DELETE_FAILED_DEVICE_POLICY_MANAGER]

I tried to force stop the app once the tablet boots, but it just starts again as soon as it closes and then starts back into the reboot cycle.

adb shell am force-stop net.soti.mobicontrol.elm.samsung

For the factory reset, it doesn't seem the device is staying powered on long enough for the command to take.  I am trying to enter the command as soon as I see that the device is fully booted, but it doesn't seem to be completing and then the device continues with it's rebooting cycle.

adb shell am broadcast -a android.intent.action.MASTER_CLEAR
Broadcasting: Intent { act=android.intent.action.MASTER_CLEAR }
Broadcast completed: result=0

I'm open to any other ideas to try.

So I'm not really sure what changed, but I can get the tablet to stay powered on now.  I'm not sure if one of the adb commands did something or not, but it doesn't reboot automatically now which is good.

Now, on to the next issue.  The Kiosk profile is being attached to the tablet, which I can get out of by holding the back button and entering the admin password.  How can I disassociate this device with the non-existent deployment server from the tablet since I have no way to un-enroll at the server level?

Scratch that, I figured it out.  I held down on the Enrolled section in the MobiControl app and got a pop-up to un-enroll the device.

I believe I am good to go now!  Thanks Raymond for the suggestions which led me down a path to getting this resolved.

Hi Chris,

It's great to hear to have your problem solved.

You are lucky that you can unenrol  the device from the "Enrolled" section in the MobiControl app.  I usually leave that loophole untouched when testing new device features, but will always have it blocked  for production devices.

 Actually, the three ways I suggested in my earlier post to you won't work for most of my customers because they would follow our recommendations to use the right device brand/model and MobiControl policies to have all such loopholes blocked.

That's a good point.  I definitely wouldn't want our customers in the field to have the ability to do that.

Let's say I did have that locked down, how would I have gotten this resolved in this case?

There is no single simple solution for all device brands/models.

Reboot cycle due to firmware incompatibility should be avoided in the first place by blocking automatic firmware upgrade on production devices unless compatibility of known target firmware version has been confirmed on test device of the same model and configurations.

For device agent un-enrollment, the best scenario from security point of view is to disallow it altogether by device end-user.  It would be even better if the device gets re-enrolled automatically if it is factory reset.   This is achievable with DEP (Device-Enrollment- Program) for iOS devices,  KME/KC (Knox-Mobile-Enrollment/Knox-Configure)for Samsung devices and ZTE (Zero-Touch-Enrollment) for Android Enterprise (AFW) devices. 

If all the previously posted three ways are already blocked on your Android devices, you may be able to initiate device factory reset by intentionally inputting wrong passwords many times for some device models.  For some of my cases, I can use a pre-pushed proprietary app to force factory reset upon special trigger event(s) on boot-up.

I know it has been a while for this post but maybe this will help someone?

One of the things we have found that causes this reboot loop especially in older android devices is when an android device detects a new network it will try to send a notification to let you know. We were blocking those notifications in Mobi control and it was causing our devices to crash and reboot. As long as we were connected to our default "pushed" wifi setting, it worked fine, but as soon as we go out of the range of our private network, Reboot city. 

We found that if we go under wifi settings and turn off the option to notify when a new network is found, the devices quit rebooting.

It took a Sonim engineer, myself, a Mobi support technician, and a whole lot of sleepless nights to figure it out.

I haven't seen the problem since we upgraded from android version 4.4.4 to 5.1 and now to 8.1, but if you're still using older android technology it is something to think about. 

We still have a lot of those devices in the field and it gets us every time we reconfigure.