So actually you have the original FW but you are having issues with it?
I’ve had no experience of the R8 but there is a Linknode R4 Wifi 4 Ch Relay Board discussion you might find useful, FWIR the R4 firmware from that same repo worked fine. ASFAIK that is the original FW but I have never reinstalled it to know for sure.
Are you following the R8 wiki page instructions for installing the R8 FW in that link?
When it compiles are there any error messages?
When it runs what serial output are you getting?
BTW the linked sketch creates an AP accessed via 10.0.1.1 not 10.0.0.1. However if the WiFi AP isn’t being made available the IP address alone won’t be the problem.