Hi all, I need some urgent help with my mk 3 Fiesta if anyone can help....

I Have been having problems starting, appearing to be a discharged battery.

I have fully charged battery off car. Still turns over a bit sluggish but starts.

Battery tests out OK. Charging from alternator checks out OK.

However...

When I switch the lights on, whether side, dip or main the main beam warning light is on and there is a loud buzzing noise from somewhere in the dash area!

Main beam warning light goes off and buzzing stoops when lights switched off.

Any help appreciated, Thank you )