Before the build was started the donor frame was checked to make sure it was suitable, and worn or defective parts are replaced.
Some things to check …
Motor mounts, their security and condition of the rubber dampers, Propellers and their attachemnt
Folding mechanism function and the attachment of the locking mechanis
Integrity of the frame centre section, all screws and mounting plates, landing gear attachemnt, battery tray
Power distribution system and attachment of motor power wires.
Functioning of each motor, I used a servo tester to spin the motors.
Functioning of the landing gear, again a servo tester can be used with power applied to the drone.
A full check should be carried out of all items to ensure you are satisfied the frame is safe to use and any parts needed should be replaced. This is not an exhaustive list.