Won't start - 06 Pete 387

I will try to be brief, but I'm stumped. 06 Pete 387 915k mi went to start and turned over slow typical of low batt voltage so I fired up the apu and it wouldn't even start got it jumped turned the key - and
nothing like power was completely dead. So I tried my signals
and my dash lites came on but no blinkers no hazards. Parking lites on the roof were lit up but
not on the headlights or tail lights on tractor And Trailer. Then my gauges started going wild from right to left and both abs lights stayed lot but cycle through all other indicators. Was able to remote start it but only cranked good-DIDNT Fire up.

performed the usual checked all grounds cleaned all battery posts tightend All. Cleaned around starter alternator tightened check all voltages found one
battery won't hold a load. Replaced. Checked wired for rubbing corrosion or weAr. Negative checked all fuses not one bad.
Totally stumped as elog not showing any codes and several good mechanics and calls to Peterbilt everyone still scratching their heads. Spent 12 hours troubleshooting and all the symptons are the same. Domes, apu, pw, cb, stereo all work please please give me your thoughts. I towed the rig to my mechanics and need to get this figured out

thank you

 

Lol his meter needed a battery. Got a different Meter. Turned out it was a bad battery, broken wire and a mega fuse

 

And knowledge