PeterJames

No easy way to unlock it unfortunately the panel is over 15 years old and obsolete, its likely to have unreadable keypad pretty soon its a common problem with old Gardtech's

It has to connect to the cloud first though. When its first powered up it doesnt know what day of the week it is let alone the right time. A bit like you when your alarm clock goes off on a Thursday morning after youve been down the pub the night before for pool night

Red light= normally a fuse blown, or no battery connected. Disconnect everything at the PSU if it still shows red then you know its not any of the wiring causing the PSU issue. Check the backup battery. Im guessing from the state of thos connections its not been under a service agreement so the battery is probably over 5 years old and may be pulling the psu down

When you completely down-power It remembers the codes zone settings ect in the NVM. But it wont keep the clock going while its down powered, that will default to watchdog

Word of warning with shear locks alignment is critical any play on the door forget it, use lock tight on the screws unless you want to keep going back and adjusting it, lastly pay close attention to the instructions, they come with different springs for a reason. Surface mounted shearlocks need the right springs, (see above) but generally wont need high level carpentry skills, mortice is a different story altogether. Personally Id sub fitting a mortice shearlock to a locksmith they will do a neater job of fitting it and getting it spot on, just put the wires in the holes is my advice especially as you have never done one before. https://www.aldridgesecurity.co.uk/adams-0003-adams-rite-1354-0100-mortice-shear-magnet.html Thats where our locksmith gets his

just snip them individually that way you will know what colour goes where when you put it back/replace it. No need to down power completely just be aware the alarm will tamper

It puts more load on the psu it pulls more current than the psu is designed to provide, and eventually burns out the charging circuit

Im glad you didnt call it tape of colour

You could maybe fit a morticed shear mag, or a shoot bolt. But I would probably go with Steves idea and fit an external mag on the outside and use star screws or anti tamper screw heads to prevent someone unscrewing it or a architectural mag https://www.cdvi.co.uk/products/categories/magnetic-architectural-handles/

did you look in this box?

19vac normally

Its likely one of the diodes has blown, sometimes you can tell which one because the diode splits or looks wet, other than that you would have to desolder each one and measure it. Also look closely at the board both sides you may have burnt a track. Burning smell is another big give away that something has blown

Reversing the polarity may have damaged it, it probably at least discharged the battery. Down power completely for 5 mins then power it back up. Or down power it leave it to charge for a while then power it up