Speaking only of my MH(see below), I had a very similar problem -no power to transmission pad.
Cutting to the chase, the problem was a loose connection on the firewall(outside). There is terminal block where power comes from the chassis batteries and from the terminal block is disseminated to the shift-pad, dash instruments, etc.
It took a mobile mechanic and me 1.5 hrs to find the loose connection, he tightened the retaining nut and everything worked normally, has ever since.
2000 Winnebago Ultimate Freedom USQ40JD
, ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG 11B5MX,Infantry retired;Good Sam Life member,FMCA." My fellow Americans, ask not what your country can do for you, ask what you can do for your country. John F. Kennedy