Go to https://support.microsoft.com/en-us/surfacerecoveryimage (with a different Windows computer if yours is not working properly, use any Windows computer - it does NOT have to be a Surface) and download a recovery image for your Surface. You will need a 16GB or 32GB USB stick (also called a flash drive) formatted FAT32 (use a Windows computer). You can't use an actual external USB hard drive for this and don't use anything larger than a 32 GB USB stick. Best to purchase and use a new, previously unused USB stick for this. Use FULL format and not quick format and give the volume a name like surfboot. Unzip/extract the recovery zip to the root of the formatted USB stick.
To reset your Surface from a USB recovery drive:
Step 1: Make sure your Surface is turned off and plugged in (hold down the power button for 30 seconds).
Step 2: Insert the USB recovery drive into the USB port on your Surface.
Step 3: Press and hold the volume-down button while you press and release the power button on your Surface.
Step 4: When the Surface logo appears, release the volume button.
Step 5: When prompted, select the language and keyboard layout you want.
Step 6: Select Troubleshoot > Reset your PC.
*If prompted for a recovery key, select Skip this drive at the bottom of the screen*.
Step 7: Select the target operating system you wish to reset. This refers to the current operating system installed on your Surface.
Step 8: Select Yes, repartition the drives, and on the next page, select Next.
Step 9: Choose Just remove my files.
Step 10: Select Reset.
Surface restarts and the Surface logo displays while the reset process continues (this can take a while).
If this fails, you need to purchase a newer device.