iPad Pro 9.7 - 1st Gen - Smart Keyboard(s) won't connect

Hit the end of the road here, so looking for any other solutions!

As per above, I have 128gb wifi/cell version and I have loved it for many years.

In 2018 I had my original Smart Keyboard replaced, as it had connection issues. No problems with the replacement until early March at the start of lockdown here in Spain. A very common issue as per many threads here and all over the internet.

I had a so-so response from Apple, noting that the replacement keyboard should still be covered by the 3 year extended warranty. But given I couldn't get to an Apple Store, I ordered a second hand one online.

This worked perfectly for a couple of weeks, then started showing the same issues, and now again will not connect at all - perhaps 5% of the time it connects, but type two sentences, and it disconnects again.

I have followed all suggested Apple processes, and some others across the internet including :

• full software wipe of iPad, and start again (not from a backup)
• multiple (daily?) forced two button restarts
• cleaning of contacts on both keyboards, and the iPad itself (though I haven't used anything chemical, just a damp cloth)
• The 'magnet' trick as described in a few places across the internet. This seemed to have some initial success, but now doesn't achieve anything

Interestingly, while it doesn't fit particularly well, my wife's 10.5 inch Smart Keyboard (older than both of mine, as it has never been replaced under warranty) continues to connect and work successfully!?

Apple Stores have still not re-opened here, so I can't visit a Genius to discuss.

I don't think I've missed any advice here, but I'd be curious to know if there are any other tips?

Thanks!

Justin.