Troubleshooting not working

So recently my Xbox has been very buggy, I have been getting black screens, lag, crashing and now my troubleshooting won’t work, I’m taking the power cord out, waiting for 30 seconds, plugging it back in then holding the bind and sync button but nothings happening, and I’m having no signal so basically my Xbox can’t even work now, I’ve tried so many things like plugging the power cord out the wall, turning off the internet but it won’t work, does anyone know how to fix it and if anyone does, please tell me how to fix it.

:)