1. Outdoor unit approx 1.5 years old. Installing contractor added ***** per owner.
2. A week later company B says it is low, evacuated, added *****, came back the next day to add more refrigerant since he did not have enough *****. Tech says compressor is seized.
3. I arrived and found J5 alarm, compressor/cond fan would not start. Ohm out 4 sensors on X12A. R2T disch sensor only 1K, R3t and R4T sensors good( suction line and coil), R5T sensor suction 2 sensor was open. replaced the sensor from a brand new unit, R2T approx 17K is good but the suction 2 sensor R5T was open open too. Outdoor unit started.....cond fans ramp up tp full speed in approx 10 seconds then shut off, comp then ramps up in 3 seconds about 22 amps on all 3 legs then ramps down in seconds, no comp noise or clunking noticed, no alarms, then it repeats this again in a few minutes.
4. I ran out of daylight but I do not feel comfortable with a defective compressor. I downloaded the correct model manual this am.

Questions
A. J5 alarm could be the suction 2 sensor still and the discharge sensor R2T did not alarm even though it thinks it is below zero? Why is the unit trying to start now when R5T is still open?
B. I did not static test diodes or have an inverter checker last night but is it possible that the board is bad? I didn't test because I assumed the comp should spin if it was drawing amps?
C. Why isn't there an alarm when the comp does not start?

Thanks for any help