my new laptop's battery is screwed and I have to take it back for a replacement - recently downloaded GUI and transferred a decent level of Monero into it.
Before taking to the service center should I delete the GUI or just rely on my password - yeah n00b question - but I really don't know who I should trust anymore, reading all this crypto stuff has made me paranoid!
Your password should keep it protected but its probably advisable to at least delete your wallet (found in "C:\Program Files\Monero wallet" I think) as a malicious person could still copy, and brute force it. Alternatively you could simply generate a wallet on a new machine, and transfer them.
Excellent question. Little anecdote: I just read in the local newspaper today that people who bought a "new" laptop, are occassionally given a "refurbished" laptop, containg holiday pictures from a previous customer … That is scary, and therefore, you shouldn't trust any service center.
I think you have 2 options:
Safely erase then entire disk one of the methodologies listed in this Wikipedia article. Depending on your OS, there might be a feature to accomplish this (e.g macOS supports some of those), or you may require external software. However, safely erasing the entire disk may render the servicing impossible if it is a software issue they need to investigate. If you have an SSD, it might not be recommended either for technical reasons.
Probably the better choice, is to transfer your entire Monero wallet amount to a new address that you manage on a different computer. This makes sure that, even if the service center obtains access to your former wallet, it is empty and useless.
If it's a hardware issue not related to the hard drive, I would just remove the hard drive before sending it in. You are giving your laptop to complete strangers and who knows what their security is like.
There are too many stories about employees at computer repair shops snooping in other people's files, copying private pictures and uploading them to the Internet, and anecdotal stories of people's Bitcoin wallets being emptied. It recently made the news that law enforcement is paying bounties to employees at repair shops for reporting illegal content. Now there is an incentive for them to snoop even more, or maybe even plant content.
I would say write down your mnemonic and wipe (securely) everything Monero on your computer (and anything else that corresponds to money). Its possible that someone in the service dept installs spyware on your computer if he knows you're using Monero and wants to steal it. If there's nothing interesting on your computer, he probably won't waste his time with it.
You can re-install Monero when you get it back and use your mnemonic seed to recover your wallet.
