Problem:

I failed to update Xhorse Dolphin XP005L firmware from 3.2.1 to 3.2.4 within tablet. After upgrade it went back to version 3.2.1 and gave the error “Charging board in BIOS mode”, any solution?

VVDISHOP solution:

Unplug the green communication cable of the battery pack (image below).

Turn on Dolphin II and update firmware again.
Then turn off the machine, reconnect the green cable of the battery, update again.