Answered your mail and for sure I have only s1300-factory-to-openwrt.img these used. That was the problem in the other tutorial apparently, sounded like you should use both and then flash OpenWRT, I test it again to be sure but theres a connection reset after pressing the power button, just only the network logfiles, which doesn’t help much. 100% I’m not yet.

@fellow gl-inet-users just a PSA:
If one of you has the idea to try this also, the “wrong” tutorial by a user I posted above is now flagged correctly as wrong, it’s highly probably correct what @hansome posted and I’m sure if you follow his tutorial exactly it will work. But remember apparently is it relatively easy to brick your device compared to the “undestroyable” travel router ( & all with older chipsets basically) series. The official firmware is for both the B1300 and S1300 to find here just update this, just my advice because it’s apparently IMO not worth it. They get regularly updated, including a clean openwrt release.