Codes P2817 and P0700?

The check engine light came on and these are we used a code reader and saw these 2 codes P2817 and P0700. We did not drive the car once we saw the engine light. There were no other symptoms: no hard shifting or delayed shifts, no "limp mode" and no gas mileage changes. We took it to a repair shop who recommended a transmission clean solution and flush. The repair shop checked the transmission fluid pump, it was working, and the wiring to the solenoid and voltage was good. The codes came back and he said it could be the solenoid or we could need a new transmission as the clutch could be bad. All the reading I have done says the transmission would first go into a limp mode to prevent transmission damage. Also, the codes for transmission internal repairs are usually P0700-P799. He said he could replace the solenoid, it is a kit. But if that doesn't fix the problem, we would need a new transmission, which includes a new solenoid. So we would be paying for the first repair twice.

Everything I read says a transmission replacement would be a misdiagnosis. That replacing the solenoid, wiring or reprogramming the PCM are usually the fixes.
Do you concur? What else could be checked to prove it is the solenoid or PCM and not the clutch in the transmission.
Also, the mechanic took it for a test drive and said he did not notice and transmission problems on the drive, but the light showed "pending" on their code reader for the same codes.