at start shows -surface then turn to black screen

Hi Ivan, I've had that same issue with my Surface Pro RT tablet. Plug the tablet in, and let it charge, then hold down the power button for an extended period, it should bring you to a blue screen. (For once we want this color ;)

If a hard reset doesn't do the trick, then you must do a usb restore.

When you set up this tablet, it forces you create a MS account. Log into that, and you will see all the information about this tablet, your recovery key, ect.

Download the recovery onto a usb drive, the website is very easy to navigate and this will not be difficult to locate, then try to turn on the tablet. If all goes according to plan, it will boot from that USB stick. Now, depending on why exactly your tablet is acting up (shutdown during an update, or just an 8.1 crash..) you may loose everything that is on it. Hopefully you can keep your information, but I would rather have a working tablet, than a paperweight.

Good luck! and believe it or not, the MS website is very helpful with this, as long as you know your logins, or at least what email you signed up with.