Keyboard randomly and intermittently uppercase, combining letters, not working at all

[KafountineKate]

Over the last few months our HP Pavilion Gaming 17 cd0077nf running Windows 10 21H2 has frequently (but intermittently) started locking/unlocking Caps, the shift key sometimes seems stuck on, as does Ctrl (multiple widows and files opening etc), bizarrely lately the b and g keys pressed individually produced gb combined, as do h and n (hn)  Sometimes the keys do not work at all.   It is a French keyboard and set as French.  The language of the laptop is set to English and changing that to French changes nothing.  The glidepad/pointer are not affected.
Problem is the same with an external keyboard
Have updated Windows, and have the latest BIOS offered by HP - F.50 vA
Problem is the same in Safe Mode

Have run HP Hardware diagnostics UEFI on memory and quick Hard drive test - both passed.  It is now running a detailed check but that's clutching at straws..
Went to check keyboard in BIOS but though the BIOS screen appears, keyboard arrows do not work, can only access the field in focus (i.e. the date)   Anything other than Enter just beeps at every key depression.  Caps Lock light flashes on and off randomly, does not appear to be an error code, too erratic.

There seem to be a few people who have had exactly this problem over the years...but I haven't spotted any resolutions yet.   Any help greatly appreciated!  We don't use this as a gaming PC, we got this spec because of some music software. 
I hope the answer is not to take it to a specialist because we are out in the West African bush, and though lots of electronic gear gets repaired here against the odds, I think this one might be beyond my usual contact!

[CharlieItuah1]

These troubleshooting steps start from the easiest and most likely to work to the hardest and least likely to solve the problem.

Try these tips in the link provided. Let's see if it works out.

https://www.lifewire.com/fix-non-working-keyboard-on-hp-laptop-5116124