I had exactly the same issue, new MK had been working fine for a month, all has been fine, the suddenly last night. Nothing, no track pad, and couldn’t even type with. The keyboard, Searched everywhere And found someone mentioning about charge cable being connected.
Anyway, how i recovered the operation, plug charge cable into the ipad, and NOT into keyboard charge port. Whilst it is still being charged, disconnect the ipad 2 -3 times from the keyboard, and hey presto all working again.
I did also find the keyboard very slow to respond, and found that while staying multiple things to get the keyboard back into life, i must have accidentally switched on slow keys. Turned it off. All back to working fine.
Not sure what caused the problem in the fist place, maybe it one thing to do with always using the keyboard charge port.
Anyway hope this helps.