Have you tried just dialing the sweet way back instead of cutting it cold? Half the sugar gets you the same sales without hiding the sage.

That blinking screen usually means the ribbon cable for the digitizer got nicked or isn't seated all the way, which is super easy to do on those kits since the adhesive strips they give you are garbage. My buddy did a $60 kit on his Galaxy and ended up with the same blinking mess, then paid a shop $140 to fix what the kit broke plus the original crack. The cheap tools in those kits are the real problem, the plastic pry pieces flex and you end up digging into the cable without even feeling it. Before you toss the whole phone, try pulling the screen off again and reseating that connector, sometimes it just popped loose when you snapped the back on. If the cable itself is torn though, you're looking at a new screen and at that point the shop is honestly cheaper than buying two screens.