Engine not starting, touch screen not coming on

I would be checking your new battery voltage , battery terminals and ALL earths / grounds before getting too involved

Try wiggling the gear selector as you hold the key on start position

Thank you,
The new battery voltage is 12.8v, terminals are clean.
The battery earth loom goes through a hole at the back of the wheel arch, don't know where it goes to, but looks like it might be to the dashboard somewhere ? I did notice there is no continuity from the battery earth terminal to ground, not sure if this is normal on modern cars? I will have a look at other earth points that are visible on Monday. My wife won't let me look tomorrow as I've got a big birthday.
I'll try wiggling the gear selector tomorrow when she's not looking 😀
Thank you so much for your support, I'm really grateful.

Battery is fine at that voltage . There is often an earth from engine / gearbox to body in most cars . If needed check any relevant fuses . Enjoy your birthday !!!
P.s

Brake pedal will get harder as you are using up the vacuum assistance that is created when engine running


Citroen C4 Picasso mk2 (from 2013) – fuse box diagram
Year of production: 2013, 2014, 2015, 2016

Fuse box under dashboard
The type of electrical of the vehicle depends on its level of equipment. To identify the type of electrical system on your vehicle, open the bonnet.

TYPE 1: electrical system does not have any fuses in front of the battery

TYPE 2: presence of an additional fusebox in front of the battery

Type 1 fuse box
Fuse box number 1
Fuse Ampere rating [A] Function
F8 5 Steering mounted controls
F18 20 Touch screen tablet, audio and navigation system, CD player, USB ports and auxiliary sockets (AUX)
F16 15 Front 12V socket
F15 15 Boot 12V socket
F28 5 START/STOP button
F30 15 Rear wiper
F27 15 Front screenwash pump, rear screenwash pump
F26 15 Horn
F20 5 Airbags
F21 5 Instrument panel
F19 5 Rain and shunshine sensor
F12 5 Keyless starting unit
F2 5 Manual headlamp adjustment control
Fuse box number 2
Fuse Ampere rating [A] Function
F9 15 Rear 12V socket


Type 2 fuse box
Fuse Ampere rating [A] Function
F3 3 START/STOP button
F6A 15 Touch screen tablet, audio and navigation system, CD player, USB ports and auxiliary sockets (AUX)
F8 5 Alarm
F9 3 Steering mounted controls
F19 5 Instrument panel
F24 3 Rain and sunshine sensor
F25 5 Airbags
F33 3 Memorisation of diving position
F34 5 Electric power steering
F13 10 Front 12V socket
F14 10 Boot 12V socket
F16 3 Map reading lamps in row 1 courtesy lamps
F27 5 Electronic gearbox gear selector
F30 20 Rear wiper
F38 3 Manual headlamp adjustmet control
Fuse box in engine compartment
Type 1 fuse box
Fuse Ampere rating [A] Function
F18 10 Right hand main beam
F19 10 Left hand main beam
Type 2 fuse box
Fusebox 1
The fusebox is place in the engine compartment near the battery (left-hand side).

Fuse Ampere rating [A] Function
F9 30 Motorised tailgate
F19 25 HIFI amlifier
F21 3 Hands-free starting reading unit
Fusebox 2
An additional fusebox is fitted in ftont of the battery (fot type 2).

Fuse Ampere rating [A] Function
F19 30 Front wiper slow/fast speed
F20 15 Front and rear screenwash pump
F21 20 Headlamp wash pump

If an earth suspect , you can try a temp earth from engine / gearbox to body by using a jumper lead

That's fantastic!
Mine has got the extra fuse box in front of the battery, so makes it a type 2.
Weather permitting on Monday I'll check all you have suggested 🤞
Thanks for the advice and your time .

Thank you for all your suggestions.
Tested all earth connections I could see, all seem to be good. Earth from engine block to ground seems okay on continuity test , but connected jump lead from engine block to ground anyway to make sure.
Checked all fuses at the side of the battery, and under the dashboard, all are good.
Wiggled the gear selector (Auto) still no life .
What I did notice though, the battery has been getting wet and the tray is flooded after rain. tried to find where it was coming in and put a bit of sealer in suspect joint in rubber. also have left some plastic over the battery area to keep dry for testing.
Looks like a phone call to a recovery service, and taken to Dealership ££££!

Have same problem does you found what problem was?

Firstly, thanks to whittingehame for all his help.
I had a discussion with an Auto Electrician who suggested I "jumped" 2 of the fuses in the battery fuse box, it started the car but not for long.
At least I found the problem was with the Battery Protection/Management Unit, which is directly in front of the battery.
Ordered one from dealership which cost £367!! Anyway, fitted it yesterday afternoon and it started first time and everything works okay.
Started this morning okay, so fingers crossed problem is sorted.
Hope it helps you avoid all the headaches I`ve had the past couple of weeks.
OH, thought I`d mention that my breakdown company Emergency Assist let me down badly, they wanted to charge me £321 to take my car to Windsors. Will be searching for another breakdown company.