Homebrew N3DS Screen Flickering after EmuNAND update

[HeyItsJono]

EDIT: Issue resolved itself after 50ish reboots.

So I'm having a super weird issue and google isn't turning up results. Just then I installed ReiNand 3.1 and used it to update my EmuNand on my Europe N3DS from 9.5 to 10.3 (10.3 because the update was already downloaded onto my system so it used that instead of downloading 10.4, also Tubehax DNS). The update worked fine, and I booted into Rei 10.3 Emu perfectly. I then wanted to delete rxTools from my SD since I no longer needed it, so I used CTRXplorer via the HBL Launcher .cia to delete the folder. I then wanted to edit the boot.cfg to get rid of the rxTools entry, so I went to run the microSD manager title from Gridlauncher but it blackscreened. I figured it just didn't launch properly from Gridlauncher so I force-rebooted my 3DS. Here's where the weirdness comes in; after turning it back on, the top screen of my 3DS started flickering repeatedly. This happened as soon as the Menuhax imagedisplay.png showed up, and didn't go away. It persists after a reboot, it appears in both SysNAND and EmuNAND, and it displays on practically every screen except for FTP-3DS's top screen and any screen like that where it's just text being printed. I don't think it's a hardware issue since nothing physically happened to my 3DS, I didn't force it open or hear any unusual cracking sounds or anything of the sort, it just started happening after microSD Management wouldn't boot from Gridlauncher. What's weirder is that the corners of the screen still display a ghost-like image of the Gridlauncher top screen, it's not just a on-off flicker but it's like the gridlauncher display is flickering over the top of the regular display. I'll try and get a video up soon of what it looks like
So yeah, any ideas on a fix?

 

[Osakasan]

A friend of mine got this on o3DS after the whole proccess of downgrade-create EmuNAND-Install CFW (RxTools in his case) He gets screen flickering (black to image for nanoseconds)

Honestly, it was me who did the whole proccess son i'm pretty worried, my o3DS didn't get any problem of sorts.

 

[HeyItsJono]

A friend of mine got this on o3DS after the whole proccess of downgrade-create EmuNAND-Install CFW (RxTools in his case) He gets screen flickering (black to image for nanoseconds)

Honestly, it was me who did the whole proccess son i'm pretty worried, my o3DS didn't get any problem of sorts.

It's been about 20 minutes or so now, and it's basically progressed to that. No more ghost image of Gridlauncher, but now it's just an extremely rapid flickering.

 

[Sono]

What's weirder is that the corners of the screen still display a ghost-like image of the Gridlauncher top screen, it's not just a on-off flicker but it's like the gridlauncher display is flickering over the top of the regular display. I'll try and get a video up soon of what it looks like
So yeah, any ideas on a fix?

That sounds like my phone's screen. Does your n3DS have an IPS screen? You should try to dispower the 3DS. Take out the battery, hold the power button for a minute or so, put the battery back, and try again.

Also for the flickering, if you turn the 3D mode on, what does the "right" screen do?

 

[HeyItsJono]

That sounds like my phone's screen. Does your n3DS have an IPS screen? You should try to dispower the 3DS. Take out the battery, hold the power button for a minute or so, put the battery back, and try again.

Also for the flickering, if you turn the 3D mode on, what does the "right" screen do?

5 minutes later and now the issue is completely resolved... I didn't get the chance to try this, it just randomly fixed itself after like 50 reboots. That was surreal. Thanks for the advice though, if it comes back I will definitely try this, although hopefully it doesn't come to that. For reference, when 3D was on it worked, but still flickered darker and lighter.

 

[Sono]

5 minutes later and now the issue is completely resolved... I didn't get the chance to try this, it just randomly fixed itself after like 50 reboots. That was surreal. Thanks for the advice though, if it comes back I will definitely try this, although hopefully it doesn't come to that. For reference, when 3D was on it worked, but still flickered darker and lighter.

I guess something borked the GPU state up so bad, that double buffering was enabled while the software thinked it was turned off, so it rendered to only one framebuffer, and because nothing was written to the other framebuffer, it was completely black, resulting in a black-ish flicker.

 

[HeyItsJono]

I guess something borked the GPU state up so bad, that double buffering was enabled while the software thinked it was turned off, so it rendered to only one framebuffer, and because nothing was written to the other framebuffer, it was completely black, resulting in a black-ish flicker.

It's odd that that would persist after a reboot though. I also did pull the battery when it first started happening (but I didn't hold the power button for a minute like you suggested) but that didn't fix it either. It just weirdly resolved itself out of nowhere after many reboots. In any case, thanks for the help! I'm just relieved I don't have to buy a new 3DS, particularly with 10.4 out now.

EDIT: Now that I think about it, you're probably right about the GPU thing, since it didn't trigger on screens which only displayed debug text, maybe they use an alternate method of display rather than using the GPU, similar to how there are LCD registers for solid colours that are separate from the GPU registers? Also, for reference for anyone else, I updated prior to it happening then I ran NTR CFW, entered Gridlauncher via HBL.cia after having already run a game, then ran microSD management from Gridlauncher which is probably just a trio of fuckups so maybe that was what screwed up the GPU.