to revive a car like this.
it involves completely gutting everything from the interior out, including removing all wiring harnesses, entire dashboard including firewall padding too, carefully clean out all sewage residue (imagine, feces, urine, menstrual blood etc were mixed in that water) from everything - including body crevices that are packed at factory - then you need a solid dosing of cavity wax to prevent rusting.
then rebuild the wiring and clean them of all corrossion. If any module like ABS or EPS or climate control is toast, buy replacement ones. Usually the starter and alternator would be shot too, Then finally check if the engine survived, because once you get pitting on the cylinders from corrossion or corroded valve seats, the engine needs replacing or rebuilding if possible - provided your engine has not hydrolocked, broke a rod and holed the block, if the transmission is automatic, you need 20 litres ATF to flush a 10 litre transmission and even then its a hit or miss because the friction material of clutch packs in automatic are water soluble.
While at it, put the car on jacks and inspect all wheel assemblies, if any boots were ripped on axle or joints, they are dead, the brake caliper pins would be siezed up too.
When l was in Karachi, I have revived such cars but they were an extremely expensive exercise for the owner, Best is to cut your losses and junk the car if you didnt have insurance for it. Or sell its parts on olx and sell rest of it to scrap market.
