Doof let all the gas out...
Regarding your friends gas being let out, I would take the bike to the nearest bike shop and let them re charge the shock with nitrogen. The cost for this would probably be around $20 to $30 bucks. I believe that the amount of gas is measured in psi and unless you had a gauge to measure the amount, you may get too much or not enough, therefore the shock may not perform well. As far as damage, I don't believe that is an issue. You would just have a bike that doesn't perform well.
I hope this helps.
00 KDX 200
Procircuit pipe & silencer
AMA
GNCC;)