3DS Black Screen / Freezing - Half fixed

Hi, I seem to have a weird problem

My 3Ds broke whilst it was with someone else, I forgot to ask what did they do as it happened and I can't get hold of them at the moment so not sure how it started.

It's not in warrenty so I've been trying to fix it myself as I've fixed someone's before.

I took the SD card out and when turning it on the backlight would come on but no sound or display on either screen, just black (with backlight) when I closed it and opened it the backlight would disappear like it was stuck in sleep mode - the blue light and wifi light both worked, but not the 3D light.

I tried reset, taking out battery and reconnection the WIfi chip but same problem, I thought I would just try putting a game in and it came on, it took me to the menu, sound now worked, I could scroll across and the 3D light worked, but if I tried to click on any menu it would go back to black screen and I would have to turn it off

When I clicked "manual" it freezes but with the screen on. It may need updating but the wifis changed and I can't go into the settings to change it so when I do "L,R,up,A" nothing happens

Also when I take the game back out it doesn't come on, so I can only go to the menu with a game in

Edit: just to add, once In the menu, all the square icons when clicked go back to the black screen but when I click the mini buttons at the to or the manual button it stays on but freezes (sometimes only the bottom screen freezes )

Edit 2: I took the game out while it was on the menu and now it seems to boot up without the game, still with freezing and black screen issues.

Thanks,

Nicole