Are you sure your charger is working? If there is no sign of life without the battery inserted, it might just be a bad charger. Do you have a multimeter?

Thanks for the reply!
I have tested the charger with another laptop and it works fine, it is a multi plug charger

What about Amps, powerfull enough? Does the charge light come on?

Without the battery there is no sign of life, the charger has multiple voltage settings. Should I try and up the voltage?

I remember having a Fujitsu that did similar things... starting to almost instantly power off, hard disk fails (if it gets that far)... the source of all problems was a depleted CMOS battery.

Maybe you should try:
- Disconnect your HDD.
- Disconnect additional RAM (maybe all SO-DIMMs, I've got a Toshiba that has some RAM soldered in mainboard).
- Disassembly the PC and check CMOS battery voltage.
- Check CPU fan.
- Inspect mainboard thoroughly.

Also, you can find a service manual for your laptop on archive.org. Maybe it can give you hints about how to proceed.

Hi,
The cmos battery is an unusual one, I am not sure if I can buy a new one. Do you know if there is a workaround?

Generally just match the volts and the space available. If it's a particularly small or odd shape, give it long leads and find a cell that can tuck away in some other spare corner of the chassis.

This is the battery

It seems a pair of coin batteries soldered together...

There's a flat 3 cell pack that comes for cordless landline phones, if you get one of those, cut off one cell at the neg or pos end, you just have to resolder one wire, and shrinkwrap it.

You can buy those CMOS batteries online.

Does the laptop say what voltage it expects on it somewhere?

I think for these Toshibas it should be 15 volts, and CHECK THE POLARITY.

Is it a laptop multi voltage adapter or one of the wall wart type ones?

The laptop is a multi voltage charger, here is a photo of it

for_coffee wrote on 2021-07-06, 09:38:

Without the battery there is no sign of life, the charger has multiple voltage settings. Should I try and up the voltage?

Don't blindly up the voltage. Set it up according to the manufacturer. There should be a label on the bottom side of it. I found this online:

POWER (All models)
Autosensing External AC Adapter 3.93”L x 1.97”W x .98” --- .46 lbs.
Input (Voltage/Frequency) 100-240V; 50-60Hz
Output (Voltage/Amps) 15 VDC; 2A (max)

If this is correct, set it to 15V and no more.

I had the same issue a few months ago and just bought a new battery on aliexpress.
Works wonders.

Strange as it should start anyway even with a depleted battery.
Is there a second battery, bigger pack hidden somewhere?

I'll say again... check the polarity! I can't remember whether these Toshibas want positive or negative tip.