I have 2002 S80 with about 126K miles. During and post COVID, the vehicle was used very little and the battery kept dying. I later replaced the battery, and the occasional use did not require a jump start. One night I went to start the vehicle and it would crank but no start. Below is an approximate history of the troubleshoot done to date:

1. Connected an older FIXD scanner and it reported a Cam Position Sensor and Accelerator Position Error. I replaced the Cam Position Sensor with no change.
2. I connected a noid light to one of the fuel injectors and confirmed no signal.
3. I measured the fuel rail pressure and it was > 40 PSI
4. I connected a new scanner (BlueDriver LSB2) and it reported Error codes P1630 Immobilizer and P0335 Crankshaft Position Sensor.
5. Paid a mechanic $125 to help troubleshoot and he suggested I replace the CAM position sensor again, sensor bracket, and sensor connector. I chose not to buy another sensor, but did buy the bracket and connector (both were damaged from troubleshooting). He also discussed replacing the ECM and wanted me to call when the parts arrived for him to install. Since I did not get much value from the first visit, I chose to install myself and not call him back. Still crank no start.
6. I purchased a used ECM on eBay ($63) and sent the original ECM, replacement ECM, original CEM, and keys to XeMODeX to be reprogramed($330). After installing the reprogramed hardware I got the same error codes. I reached out to XeMODeX and was told "Looks like there were some issues found on the board of the original. Some faulty components. Immobilizer sequence was good, so I'd recommend further diagnostics at this point to make sure the ECM is able to properly communicate."

I did buy a higher end scanner(Foxwell NT530), but I returned it since it did not give me any new information. I don't mind investing in tooling if it will help me (also own a 2021 Volvo).

Up until this problem, this vehicle has been the most reliable vehicle I have ever owned (bought it new). The value of the vehicle running is between $500 and $1500 USD. At this point, should I cut my losses or is there some wisdom that can be shared to help me fix this vehicle?
Thanks in advance for any feedback that can be provided.