Citroen c3 picasso 1.4 VTR+ help please

[Bingbong]

Hi, got a Citroen c3 picasso 1.4 petrol manual, 80k on a 09 plate, cars been perfect, no driving problems, it’s been left just over 3 weeks on the drive (corona virus) when I’ve gone to start it it’s dead, thought the battery was flat, tried jump starting, battery booster, still won’t start! Took it to a “mechanic” friend who said the compression is low? He thinks the chain has jumped? But last time I drove it it was fine? Water has gone down too but no signs of head gone? It did intermittently flash the anti pollution warning light? I’m lost and have no idea? Mechanic did say to get to the chain there’s no cover so engine has to come out? Any advice or help would be really appreciated Thank you

[Bingbong]

Hello? Can someone help please

[GiveMeABreak]

Hi

I think your problem is simply that your battery has become discharged and the immobiliser system is preventing the engine from starting (regardless of jump starting).

It is not recommended to jump start in any case as it won't do it any good.

You need to get the battery off following this guide (BSI Reset / Battery Disconnect / Reconnect Procedure, charge it properly overnight, and reconnect it following the guide, which also tells you how to reinitialise the key fobs.

This should also reset the BSI and if you follow the guide, re-synchronise the keys / fobs to the vehicle. It's no good doing this with a flat battery though.

[Bingbong]

Thank you, it’s my mums car so I’m trying my best to sort it out for her

[GiveMeABreak]

No problem, flat batteries can wreak havoc on vehicle electrics - but nothing that can't be sorted if you follow the procedure, which ensures the ECUs are reinitialised.