If you have used other diagnosis and the equipment is still not working, be sure to check all the leads you are using. Check the cables that connect PA and speakers, and try instrument / mic cables connected to the mixing desk. If new cables are needed, there should be plenty in the studio with you. Any ones that are not working, please wrap in broken tape and leave on the floor.
If you need any further help, give us a call on 0333 241 9598 (UK) or 1-844-274-7283 (US)
Important : You can plug mics directly into the speaker if required with either XLR or jack leads and bypass the mixer.