That is a fairly straightforward repair by a competent body shop with the correct tooling.
The last thing that you want to do is replace the panel.
If it is a good repair then you would never know.
To the informed with a trained eye, you would always spot if a new panel has been fitted.
The problem will arise when you try to sell it, believe me.
It just won't be that the residual will be very low, because you will also find that most won't touch it with a barge pole unless it is very, very cheap.
There is a stigma regarding recorded cars and that stigma shows no signs of going away.
Listen to your brother and walk away.
Cheap as you may think it is, it will only be when you come to sell it, that you will find out if it was or not.
Best to buy a straight, accident damage free, unmolested, car IMHO.
Alex.
Common for the CSC to fail at low mileage and when it does you are stuck and the box has to come out.
However, my view is that you don't have a problem until you have a problem.
If it fails again, replace it with an uprated one from CMS.
It should last many years mate.
Just make sure that the surface is dry, and is flake and grease free.
I have some other stuff in the shop that we use on smaller items which might be more suitable for your cause, it is in aerosol format so no compressor or gun required, so produces a much finer spray.
Let me check out the branding when I am next over at the shop and I will grab an image for you.
These sort of spray on rust proofing products work well:
https://www.zoro.co.uk/shop/automotive/cleaners-and-polish/tsh010-black-tetrosyl-tetraschutz-shutz-body-rust-protector-1ltr/p/ZT1036141X?utm_campaign=pla-Automotive+-+&utm_source=google&utm_medium=shopping-pla&utm_keyword=ZT1036141X&istCompanyId=6aa6787b-063e-4414-802d-129f235df603&istItemId=wtqilpqpap&istBid=tztx&gclid=Cj0KCQjwn-bWBRDGARIsAPS1svuqXSHs3uJl9nPocmHPTBjAHydxGRsXuaupGFm6ucIgMxocsqHP_ikaAsB9EALw_wcB
From Autocodes:
This code is usually triggered when a not registered or damaged key is used to start the engine. When the starting operation is carried out five or more times consecutively with the same unregistered key, the system will lock. If the problem occurs try disconnecting the car battery for about 30 minutes and then try starting the engine with a known registered key. If the problem persists you have to have the dealer erase the code and reprogram the keys again.