Do you know if you have Fastboot3DS or boot9strap? You can check by holding HOME while turning on the console, if Fastboot3DS it'll open a different menu, boot9strap it won't change anything.

If Fastboot3DS: Check your config and make sure GodMode9 isn't set as the default option somehow, maybe switch which button it's mapped to, if any.

If boot9strap: Maybe your START button has gotten stuck down somehow, you could try deleting sd:/luma/payloads/godmode9.firm for now and see if that helps, then see if your START button is working right