Please post voltages readings in this format, makes it easier to interpret.
Nice job so far.
1=0
2= -12.6
3= 7.43 ac
4= 27mv
5=37 mv
6=61mv
7=68 mv
8=4.2mv
9=2mv
10=3.2mv
11=65mv
12=62.9volts
Rebuild or repair the Protection board.
Test the relay. Mouser P/N 653-MY4-02-DC48
The coil should read around 2.2K ohms.
Transistor Q7, the relay driver is a weak point in this circuit. The 2sc1384 is replaced with a robust KSC2690AYS.
protection parts list.
awm-090 c1 0.22 25 cssa x 0.22 50 598-DSF050J224
awm-090 c2 0.22 25 cssa x 0.22 50 598-DSF050J224
awm-090 c3 470 6 cea x 470 10 647-UPW1A471MPD
awm-090 c4 470 6 cea x 470 10 647-UPW1A471MPD
awm-090 c5 2.2 50 cea x 2.2 50 647-UPW1H2R2MDD
awm-090 c6 47 50 cea x 47 50 647-UPW1H470MED
awm-090 q1 2sc869 0 0 0 0 0 512-KSC1845FTA
awm-090 q2 2sc869 0 0 0 0 0 512-KSC1845FTA
awm-090 q6 2sc945 0 0 0 0 0 512-KSD1616AGBU
awm-090 q7 2sc1384 0 0 0 0 0 512-KSC2690AYS
awm-090 d5 eqa01-33r 0 0 0 0 0 512-1N5257B
Relay, protection 653-MY4-02-DC48
You could piece-meal it by replacing the transistors, working your way back from Q7.
Replace the caps and relay as general practice.