Why didn't you just run the diagnostic yourself when you got the 16 Power blinks? It is very easy to do. Instructions can be found in the How-To's under Trouble Codes.
However, if the car gave you the 16 Power blinks on the first start up after sitting for months, without you going for a drive it most likely indicates an electrical problem. Are your battery terminals corroded, loose ground in front of battery, loose/bad ground from transmission to firewall?
As to your question, I believe the car would still start even if the ECM was bad. A car will start with a bad MAF as well, it will just idle rough and most likely shut off at stops and will re-start as if nothing was wrong.
The stage 1 TCU and ECU are no longer available as ECUTUNE has shut down. You might be able to find some from members that no longer want theirs or have extras.
I would definitely be leery, then again I would have never taken my car to a shop.
