Keyboard missing keystrokes + BIOS cannot update

Hello I have an Inspiron 7490 and have the problem of keyboard missing keystrokes. Updating drivers via SupportAssist helped for a while, but the problem seems to have returned. One item that SupportAssist was unable to help with was updating BIOS - every time it runs it just ends up saying failed. I have suspended Bitlocker, but even when I use downloaded flash utility it seems to go nowhere. The latter is super odd, it appears with missing content?? So its blank except for a text box and two buttons (1) Accept and (2) Exit. Any help would be much appreciated on either problem.