This is a known issue when updating to LabQuest version 1.5. This issue has been fixed in versions 1.5.1 and newer. Download the most recent version for free at
If you've already started the update with an SD card, it will update some parts of the LabQuest, then get stuck in a reboot cycle. The solution is to use a USB drive, copy the SD card over to the USB drive with the same files/folder locations as were on the SD card. The LabQuest will recover automatically on the next reboot.
TIL 2370: My LabQuest keeps rebooting or is stuck on the LabQuest logo screen.