Car won't start no ignition lights coming on just radio display lights up saying eco mode then sometimes it says brake fault tried jump leads but still nothing this is a c2 vtr 1.4 petrol

Does sound like dead battery . Sometimes cheap / flimsy jump wires are useless and can be misleading when not connected fully . Or if battery is really knackered , jump start may not work .

Thanks for your info battery is fine think the ECU could be the problem as keys can open and lock the boot but not the doors the rear lights work but not the front

What voltage is your battery showing ?

Battery showing 12.7 v there is no difference when you turn on the ignition with the ECU connected or not so now beginning to think water has got into fuse box or ECU as car ran fine was loaded onto a trailer then transported over a 100 miles in heavy rain and wouldn't start to come of the trailer

Battery is fine . You mention transported on trailer , nothing to do with the shunt fuse ?

Citroen C2 (2003 – 2009) – fuse box diagram
Year of production: 2003, 2004, 2005, 2006, 2007, 2008, 2009

Fuse box under dashboard
Citroen C2 - fuse box - under dashboard
Citroen C2 – fuse box – under dashboard
Fuse Ampere rating [A] Function
3 5 Airbags
4 10 Diagnostic socket, particle filter additive, clutch switch, steering angle sensor
5 30 —
6 30 Screen wash
8 20 Digital clock, controls at the steering wheel, radio, display
9 30 Cigar-lighter, digital clock, interior lamps, vanity mirror
10 15 Alarm
11 15 Ignition switch, diagnostic socket
12 15 Airbag ECU, rain and brightness sensor
14 15 Parking assistance, instrument panel, air conditioning, bluetooth® telephone
15 30 Central locking, deadlocking
17 40 Demisting – deicing of the rear screen
18 SHUNT CUSTOMER PARK SHUNT
Fuse box in engine compartment
Citroen C2 - fuse box - engine compartment
Citroen C2 – fuse box – engine compartment
Fuse Ampere rating [A] Function
1 20 Water-in-diesel-fuel sensor
2 15 Horn
3 10 Screen wash
4 20 Headlamp wash
5 15 Fuel pump
6 10 Power steering
7 10 Coolant level sensor
8 25 Starter
9 10 ECUs (ABS, ESP)
10 30 Engine control actuators (Ignition coil, Electrovalve, Oxygen sensor, Injection), Canister purge
11 40 Air blower
12 30 Windscreen wiper
14 30 Air pump (petrol version), Diesel fuel heater

Removed shunt fuse for 2 minutes and put back in made no difference unfortunately unless I am not doing it correctly ?

Recommended 10/ 15 mins for shunt fuse if it makes any difference

https://www.askthemechanic.co.uk/makes/citroen