2005 E320 CDI
Over many months now, I have an intermittent no crank, no start condition, ESP and ABS message comes up on the screen, but goes away after the car started.
Up to this point the car would always start at the second or third key cycle.
Yesterday wife and I were out for a drive, went for a hike and when ready to leave could not start the car. Removed and reinserted the key about 15 times and and car would not start.
The ESP and ABS message came up on the dash screen.
Was going to call a tow truck, but thought to remove neg battery terminal, leave it a few minutes and then hook it up again. Tried to start the car again, cycled the key 3 times, would not start, then on the 4th try it started normally. Got home and now parked so that a tow truck can load it up if it won't start. Haven't tried yet today.

Took the car to the dealer back in December to troubleshoot the issue, here is part of the dealer report,

Found code in SBC unit C25D4 for hydraulic fault, insufficient pressure supply. also found multiple codes in ESP control unit which appear to trigger message in cluster due to communication error. code 53F0 CAN communication with engine management., 4201 increase of idling set speed. and code 4A30 ECM not identified, incorrect control module.

Guided tests states control unit Eeprom error is present that the CDI control unit is defective and to replace, Checked TIPS, no related cases. Gained access to ECU and visually inspected wires and harness, no corrosion at pins, no mouse damage or visual damage to wires, all appear OK, control unit appears to be internally faulty, recommend performing software update and SCN coding to control unit.
If software and coding doesn't remedy the fault, CDI control unit must be replaced.

They ran another test when they were able to duplicate the no start condition,

Fault codes P2311 and P2312 present in ECU, no communication available with cdi when symptom occurs. Disconnect F connector and load test ground wires on pins 2, 4, 6, all wires good.
Check circuit 15 voltage on pin 19, 13.4 Volts, present from N10/1 front SAM. Reinstall connector, and cycle the ignition, car started, Attempt to install new CDI software, system will not allow new software to be loaded. ECU requires replacement along with EGR valve."

So my question to any of you Merc gurus out there,

Does replacing the ECU make sense as to cause of my no start issue. Any other insights that may be causing this?

Can I reset the ECU by disconnecting both batteries, draining all stored charge and basically resetting ECU to baseline.
I know there are companies in Toronto area that will rebuild ECU for about $ 500+ , as opposed to the dealer replacement cost of $2500.

All comments appreciated.