I thought my C-Max was immune to the radio / ACM / APIM issue but had my radio locked up once about a year or so ago. Pulled fuse 79 and everything has been normal since. The fact that you haven't been driving the C-Max much in the last few months likely drained the battery to a very low State of Charge just from normal drain when car is off. Thus, it likely wouldn't take much additional drain (say from ACM) to yield the no-start condition.
Again I can't say enough about getting the FORScan App and an OBDII Elm327 adapter to monitor PIDs including 12 V battery SOC, tire pressure, 12 V battery charging voltage, check / reset 12 V battery age, and other data. Four times in the last 5 years or so, I noted a loss in tire pressure in one tire of just a few PSI. Upon examination of the tire, there was a screw in the tire.