Turn off any anti virus software and make sure you a using the correct cable. some cables only charge you need a data cable, theres no fast way to tell the diff you just need to plug them in and keep trying. If the DJI assistant cant see the...
Is that legitimate repair quote from DJI?
Care to show us the quote break down?
Ask a supervisor to review the quote, as it seems way too high.
Be aware that DJI will not actually repair the drone.
They will just send you a brand new one...