Sam. Wish it was something we could fix at your end. But with the motor tone, light behavior, and the loss of signal power there is surely something up with the main board power supplies.
If this turns out to the be case it will be one of the rare issues found.
Been interesting to try and chase this one.
Wes, Southport NC
EXos2-GT PMC-8, iExos 100
ES ED 127, 10" LX200GPS+wedge, Astro-Tech 8" Newt, ETX-90, 60mm no-name guide scope ~ 260mm FL
Polemaster, Orion ST-80 and SAG, ZWO 290MM, D5300 astro modified
Nina, Bootcamped Mac Mini control computer, RDP to iMAC
110 amp hour lead acid deep discharge battery for field power
Electrical Engineer, Retired