But really I cannot emphasize enough how strict and overbearing they are.
"Oh that 12V backup battery pack needs to be replaced? Better get the same one from the same manufacturer"
"They aren't in business anymore but we have this 12V battery the fits perfectly, same specs"
"Nope, not certified with that system. You can start recertification that will cost ~$40M if you like"
"...."
There is so much ass covering and not wanting to take responsibility that the market is basically in paralysis.