2005 SRX was parked for three months due to an oil leak. Car ran great. Went to start it and 2 year old battery was dead. Key locked up, too. New battery did not fix it. Got the key out. Tried several times to reset the ECM with variations of removing the fuse, opening the door, and what else. OBD II code reader gave U0100 (lost comm with ECM/PCM Modular A). Tried some other things. Nothing changed the situation. Put the key in, try to start, nothing, and the key locks up. Can any body tell me what to do next?

Thank you.