Hi and welcome to the site, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.
Initially, bear with us; re-confirm and post back with the complete model number of the Gateway machine.
Please confirm that you would want a "Secure Remote Assistance"
This would only work if the computer that needs worked on is operational and can connect to the Internet.
I understand and unfortunately, "Secure Remote Assistance" would then not work.
Offhand, I am almost tempted to suspect an internal hardware issue.
Are you then considering a DIY (do-it-yourself) repair approach?
Incidentally, which version of Windows was installed in the gateway?
The basics would be to remove the old Hard drive (HDD), replace and install Windows.
Now this model (to my recollection) does not have a built-in DVD drive hence Windows can be installed using a USB Flash drive.
Would this be something you would be comfortable in attempting?
Doubtful but can be tried. However, it would require the use of an external / add-on device.