I had 6 hours of trouble last night and thought I'd share this information with you as many people will be doing the same. So here's the story:

My girlfriend bought a SteamDeck in the summer sale and I told her to get the cheapest one and upgrade the ssd as soon as it arrived. For 2 days everything worked fine. Swapping from 64GB to 512GB worked perfectly and installing SteamOS on the new drive was no problem at all.

While I was at work, she texted me that the deck was getting very laggy in games and in the UI itself, so I asked her if she had already rebooted or set any kind of tdp or performance limit (which she denied).

So she rebooted her machine from the laggy ui and it got stuck with the boot logo. After a few minutes it went black, the backlight was still on and the fan stopped.

When I got home, I reinstalled steamos for her from the usb stick we made a few days ago (went for the reimage). I tried to boot, but the same problem occurred. After a few minutes it went to the TTY login screen and asked for a user, but the cursor froze immediately. I also tried to switch TTY sessions with ctrl - alt - f4-f6 - but that did not work either.

So I flashed the USB stick again, but nothing changed. Then I deleted all partitions manually and nothing changed. I booted my windows sd card which worked fine. So I thought maybe the SSD was broken, so I went into recovery live boot with "smartctl -a /dev/nvme0n1" to check, but everything seemed fine.

I also filled the whole SSD with zeros and tried again. Nothing.

I searched a lot and somehow found this thread: https://steamcommunity.com/app/1675200/discussions/0/3410930083331964510/

Exactly the problem I was facing and I could not believe the comment the user "Healer" (https://steamcommunity.com/profiles/76561198835118084) wrote:

Same problem. It's weird, but it was solved by putting the battery in power saving mode: Enter the BIOS at power up (Power + Vol+) with the PSU disconnected. Inside the BIOS, use the D-pad to navigate and the A-button to select. Navigate to Setup Utility. Navigate to the Power menu. Select Battery Backup Mode. Select Yes to confirm. Your Steam Deck should now enter storage mode.

Then plug in the power supply and switch on the deck.

In my case, it booted correctly.

I know it's weird, but it actually worked.

Good luck with that!

And my fucking God, that thing fixed it. I have no idea why that would fix it and I'm happy for anyone who can explain it to me. I'm fucking curious :D

And my fucking God, that thing fixed it. I have no idea why that would fix it and I'm happy for anyone who can explain it to me. I'm fucking curious :D