Hmm I am familiar with the insides of automated teller machines, and their deposit mechanisms do not actually verify the deposit. That is done by hand at the banks processing centers.
Did you replace this hardware with something more along the lines of a bill validator from a vending machine? The deposit needs to be verified before bitcoins can be sent out.
Most Bank of America ATMs that accept deposits also count and validate the bills inserted. I haven't yet noticed other banks employing this technology, but it does indeed exist.
Yes. I've seen ATMs like this (out of US)
How much does an ATM cost?
Buying an ATM would not be hard but buying one that receive deposits could be hard or expensive.