JVL
BTW it would be nice to know your name and location.
I understand you did conversion and connected non-EPLUS battery according to my schematics.
It had been said before but once again:
Display/contr. is a master and motor electronics and batt electronics are slaves.
whan you press POWER button you initiate communication protocol called RS-485 , simply disp/contr. sends enquiry to batt electronics and next to motor electronics.
ERROR1 means no successful attempt by disp/contr. to comm with battery electronics.
your problem is faulty processing board of batt electronics. batt electronics consists of upper and bottom boards: processing /also called control/ upper and power board below.
as it was said many times in this thread: disconnecting EPLUS battery from electronics is kind of tricky if done in a hurry and by not careful person.
it takes only miliseconds to damage upper board by causing short.
boards and terminals MUST be wrap with electrical tape and Allan key wraped before touching boards with tools.
main processor on upper board rarely gets damaged and such board can be repaired
Miroslaw