you have an error related to REFERENCE section (A9 + A20). The HW error #5 could be the result of that, so you should try to fix the REF first.
The ILD test stops at the first error which in your case is in the reference board. you can run individual tests for all other sections separately but it is better to start by fixing the reference section.
do you have the 10MHz output on the back of the unit? if not, your timebase osc might have problem. you can try to feed a 10MHz to the reference input at the back
which of the red LEDs on the I/O board remain on? In normal operation they must all be off.
there are three outputs from the reference (A9) at J1, J4, J5. you can easily disconnect them and examine on (50ohm input) oscilloscope.