Installing Firmware on BPI R3 Mini

Hello everyone, I am in possession of a BPI R3 and R3 Mini, with the R3 I get along so far and also had create a documentation + 3D print made for it at that time, now I am again facing a problem. The R3 Mini unfortunately has no SD card slot and I don't know how to flash a firmware via TTL. If anyone has a solution or even instructions, I would be very grateful

RTFM ?
https://wiki.banana-pi.org/Getting_Started_with_BPI-R3_MINI

oha thank you very much, I was looking for exactly these instructions

Were you able to get the BPI-R3 Mini to work with a OpenWRT image, or were you stuck with the MFG's old image?

BPI-R3 and R3 Mini look very similar at first glance, but I have not gone through enough (yet) to see if they would really use the same image.