if this is an electric 3 wheel sitdown, and i presume it is by you posting this in this forum thread, check the kickpanel (behind your legs), and also check along the front between the mast and front, sometimes they put a dataplate there. On these trucks they also stamp the serial number in the frame along the right side of the battery box.

without a serial number it will be hard to help with your diagnosis and give you accurate help.

as for the exclamation symbol showing does it have any other symbols showing? like a fork symbol or a motor symbol? generally it will have one other symbol lit up designnating which system along with the !.