Reactivating Dead laptop

I have a Lenovo IdeaPad 3 14Hl05 laptop which was originally my late brothers. I reset it to factory settings to give to my grandson some months ago. Due to complications this is only about to happen now. Unfortunately the computer appears to be dead. I have opened it up and have discovered that both the CMOS and main rechargeable batteries are completely dead and the main battery won't recharge. I have now replaced both batteries with new ones but the computer still won't boot, indeed the switch light does not come on when the start switch is pressed nor do any images appear on the screen Incidentally I think this laptop was originally on Windows 10 but was factory upgraded to Windows 11
Is there anything else I can try to reactivate the laptop or is it now irreversibly dead?

It seems that your MoBo is dead. If it is, nothing you can do will bring it to life again.
I have an old HP that was given to me and the MoBo was dead. I found a new MoBo on a site and it's working again. But to change the MB on a laptop you have to disassemble it entirely. Mot an easy task.
I suggest you look and buy a second hand laptop to your grandson.
Does any light comes on when you insert the battery charger?

@alart


Try it with the actual power cord. If you get nothing with the power cord, then...
It probably is dead, but at least I can give you ten points for filling out your computer specs.