Issues with car power inverter

When I connect battery and turn the inverter on, the led becomes red, and inverter starts to beep. It is like four beeps and pause. Load has no power.

Since the inverter was bought second-hand, I don’t have any paperwork, or manual and can’t find any neither on your website or anywhere in the net.
Could you please send me manual, or explain, what is meaning of that beeping? Or send me fcc id, so I can find it myself? It is 230v version with single UK/EU socket. Since there are no writings or labels, but Aukey 1000w power inverter, I assume, from what I found, the type of inverter is PA-V22.
I tried connecting with different cables, recharging battery, connecting to a running car, neither try was successful, just can’t rid of the beeping.

Thanks in advance


here is the photo of the inverter, just for reference