Just finished my first 5" build yesterday (Nazgul frame, Mamba F722 stack, Emax 2207 1700KV motors) and took it for a short hover test today. After about 90 seconds of gentle flying, I noticed the XT60 connector on my battery had partially melted and was quite warm. The ESC and motors felt normal temp-wise.

I'm running 4S 1500mAh 45C batteries and checked all my solder joints twice before first flight. Could this be a current draw issue or bad connector? The drone flew perfectly but obviously something is wrong here.

Any ideas what I should check first before my next flight attempt?

Almost certainly a cold solder joint on the XT60. Even tiny resistance creates huge heat under load. Re-flow both positive and negative pads with fresh flux - the joint should be shiny and smooth, not dull or bumpy.

Had the exact same issue on my second build. Check if you tinned the ESC power pads properly before soldering the XT60. Also make sure you're using 12-14AWG silicone wire, not the thin stuff that comes with some kits.

This happened to me too! Turned out I was using a cheap XT60 from AliExpress. The genuine Amass connectors handle the current much better. Also double-check your motor timing in BLHeli - wrong timing can cause excessive current draw.