Pylontech ALM LED solid red and no charge/discharge. What protection tripped?

Plain explanation

From the Pylontech manual for the US5000: Temperature >60 °C/<-10 °C → move to 0–50 °C. Current >90 A or charge V >54 V → change inverter settings. The rest of the checklist is below; work through it in order. Installer only: DC and AC work on a live PV system is dangerous, so owners should note the code and call their installer.

Steps from the source

1. Temperature >60 °C/<-10 °C → move to 0–50 °C
2. Current >90 A or charge V >54 V → change inverter settings
3. Low V ≤44.5 V → charge until red off
4. Cell V high → charge 53–54 V / cycle to balance
5. Permanent protection → distributor repair

Source

Where installers ask this

• Can't connect US3000C battery to ME3000SP inverter (r/SolarDIY)
• reddit.com/r/SolarDIY/comments/x5xhsc/
• reddit.com/r/SolarUK/comments/1k51sqd/

General guidance based on the manufacturer's manual or the named source. Always follow the current manual for your exact model and your national code. DC and AC electrical work is for qualified installers only. Not affiliated with or endorsed by any brand named; trademarks belong to their owners.