Honeywell TrueIAQ

I installed a Truesteam 9 gal. but when I fired it up the TRUEIAQ screen was blank. I gave up and called my HVAC buddy. He said I had it wired right, and he confirmed there's power to the TrueIAQ, but he says without a screen, no way to tell if it's actually doing anything.

We ended up installing a manual humidistat and all is working. But I'd still prefer the IAQ. I bought a 120/24v ac transformer todayt and hooked that up to the R and C on the TrueIAQ. Still nothing. Screen's blank.

Is there a way to tell if this thing is toast?

Thanks. Dave in balmy (today at least) Whitby Ontario.