BYD Battery-Box HVS/HVM has no LEDs and won't start. What's the start-up check?

Plain explanation

From the BYD manual for the Battery-Box Premium HVS/HVM: Check the minimum module count (HVS 2, HVM 3). Battery off: hold LED button 5 s. 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. Check the minimum module count (HVS 2, HVM 3)
2. Battery off: hold LED button 5 s
3. Installer: inverter DC off, then AC off
4. Wait (1 min BCU2 / 10 min BCU1 guide)
5. Battery on → AC on → DC on

Source

Where installers ask this

• Kostal > Batterie (BYD) temporär deaktivieren? (r/DeutschePhotovoltaik)
• reddit.com/r/solar/comments/1fjv85v/

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.