Battery plugs are slighlty different between manufacturer but are mainly a universal fit, the key your on about is easily removed with a file or modeling knife just note orientation when you plug it in.
Swithces do go duff but normally they just dont work or make a contact.
To me sounds more battery orientated than anything else or to eliminate it, how charged is your reciever pack or has it false peaked during charging, a simple check that has always worked is when its fully charged it will be warm.