Asked to work on an old Omron Sysmac C20 and it is blinking Alarm / error. No print. Was running great.
LU and LD lights are on at the same time? tried to attach photo but it was too large.

Just wondered if anyone knew how to clear it at least once or the process to clear it to see if it will stay cleared.

Attached is photo

Most likely you lost program inside ,check PLC battery with power ON if it reads less that 3 v then replace it with power on and turn power OFF cross your fingers turn back ON

is the power supply inside the plc at the bottom ok? ive replaced them and cured that problem before without a need to reload the program. do you have the ormron laptop tool? you can reset it with that.