Remove the fuse from the fused spur underneath the controls..... ?
On the circuit board there's 4 diodes, which create a bridge rectifier, the prolonger current & heat from charging a duff battery knackers 'em
Normally a consumer unit has little sticker with the companies name,
When you purchase a property you should get the electrical certificates or get a periodic test undertaken at the seller expensive before exchanging
Depending on date of works & assuming your in England or Wales you electical work may recording on the Councils planning portal