What is the best way to test coax for damage, ie nailing

Cheers

It may be too late, but......

If your nail has connected the shield to the conductor, you can check it very cheaply. Unplug each end of the section you want to test. Use a digital multimeter (beeps when you connect both probes together) to make sure there is no connection between the outer braid and centre conductor.

Put one probe on the braid, the other on the centre. If you get a beep, it's bad.

This only tests electrical connectivity, not the quality of signal delivered, etc as the oscilloscope tests above would do.