Looking for a tech in salisbury area

[Kevin moulding]

I have a g and g l85a1 with etu that I have had upgraded at daves airsoft and skirmishes it a couple of times.great gun.went to take it on my latest skirmish and it wouldn't work with the batteries I have after chargingthem.tried x2 Lipo 11.1v and x1 nihm battery I have.im sure it's something very simple.but not being the sort of bloke who dares to open my gun (cos I won't be able to out it back together).would appreciate a diagnosis from a decent tech.