If iGS620 / iGS618 is stuck, frozen, or otherwise unresponsive:

Firstly, pls upgrade the device to the latest firmware V1.23 and try again.

Check the related articles with firmware upgrade :

https://support.igpsport.com/hc/en-001/articles/900001781783-Upgrade-Firmware

Secondly, pls try a forced reboot or factory reset as described below.

• Forced reboot: Hold down the Left button for 10 seconds to perform a forced reboot. e.g. Generally used if the screen becomes non-responsive.
• Full power cycle: Should the issue remain after a forced reboot, allow the unit to die completely then charge for 1-2 hours.
• Factory reset (option of last resort): accessible from iGS620's Settings page, then System>initial Setup>Reset Setting, this option restores all settings to factory defaults.
  Warning: a factory reset will delete all settings stored on the device (routes, however, will remain).

If your iGS620/iGS618 reboots continuously,pls help to submit a ticket to contact with iGPSPORT customer service.