Dry camp I had a similar issue last year, after getting a jump start on chassis batteries, it was the 150v fuse that is between the solenoid where your emergency start circuit relays are . On my unit it was in the electrical Bay where the inverter sits.
Try this after you get your unit started hit the auxiliary start or emergency start see if your dash lights up, if it does that may be the issue.
2004 GB 3750DS Bellagio 38ft DP Freightliner XC , CAT 3126E Allison 6 spd. 2015 Cherokee Trail hawk toad.