PM4 dead - help!

[Esp1Holm]

My SkiErg PM4/2013 has been running on D-cells batteries.
Today I wanted to replace as they were getting low.
On dismounting the first of them, I saw an light-arc over what the contact for which I think is for serial connections between monitors. I don't understand why - I was removing the battery with my hand grip only.
I then replaced both batteries, but the PM4 is absolutely dead - no response at all.
Before starting replacement, everything was working fine.

What happened? Is there any fuse inside it?
Is there some parts I could replace inside it myself in order to fix it?
Any possible tips on error search, or will the whole unit need to be replaced... which I hope not.

I live in Norway - these things are quite expensive over here...

Posting in both SkiErg forum and Rower forum as the PM4 I assume are quite identical.

[Citroen]

On dismounting the first of them, I saw an light-arc over what the contact ...

If you've given it a static shock then it's quite likely a dead PM4. Low voltage electronics doesn't survive a static discharge.

[Carl Watts]

Sounds like you had a static buildup on your body and you just killed your PM4.

Pretty unusual I would have though, were you changing batteries while it was plugged into anything else ?

I usually take it off the rower and unplug everything. Will make sure I take it to my anti-static bench as well from now on !

[Esp1Holm]

It was still plugged into the SkiErg, which was not running and had not been running for days. Apart from that not connected to anything.
The spark appeared just as I removed the first D-cell battery.

Should probably have dismounted it from the Erg, but I don't think the instructions says anything about that. Would be pretty unusual I think (you need a wrench..).

[Citroen]

You should have an earthing strap or at least touch something that's grounded if the weather is dry and the humidity low enough to let you build a static charge by walking around.

[Esp1Holm]

Never loose faith!
I dismounted, opened, loosened and reconnected all the cable connections that I found, searched for burned connections, found none, wiped &cleaned with a dry rag, blew with pressurized dry air, put it all together - and WOW: It seems to work again - and all the log card data are there!
[

[Esp1Holm]

Don't know if the pictures will show...(Google Photo links)

https://photos.app.goo.gl/SesUQZJkr7U4r8QU7
https://photos.app.goo.gl/6Rj8LbdaEv1UmExMA
https://photos.app.goo.gl/3QmngVanmSpG4q3w5
https://photos.app.goo.gl/AaaeHf3Lu4PQbarz5

[Carl Watts]

It may just have been a case of leaving it without batteries for a few hours to ensure it fully reset.