Ecovacs Deebot OZMO 920 — Help me out error, motors not spinning

Hello, I need help with diagnostics.

Device: Ecovacs Deebot OZMO 920.

1. The robot got stuck under furniture, fully discharged, and stayed off for several days.
2. After charging, it powered on, voice works, LDS spins, but:
3. • wheel motors, brushes, and the suction fan do not start,
4. • after 1–2 minutes it says “Help me out”.
5. Sometimes the error “LDS sensor is blocked” appears, but I couldn’t find any logic in when it shows up:
6. • the error may appear after I disassembled the robot and reconnected the LDS (plugging/unplugging the connector, removing/reinstalling the sensor),
7. • possibly it happens when the LDS is sitting outside the housing at an angle, but there is no clear pattern,
8. • it occurred with both the old LDS and a brand new replacement, no difference,
9. • after some time it clears by itself, and only Help me out remains.
10. I tried replacing the mainboard: the seller mistakenly sent me a board from the 950 model. The battery connector didn’t match, but I have a T9 with the same type of battery, so I assembled the system as follows: mainboard from 950 + T9 battery + all my 920 peripherals. The robot booted up, greeted me, LDS spun, but the behavior was exactly the same: no motors, and after a couple of minutes Help me out.
11. → This rules out the mainboard as the root cause.
12. I tested all motors with a multimeter and also swapped them into a donor T9 → they all work.
13. Anti-drop sensors and bumper microswitches were checked — they respond correctly, and when triggered, the robot reports separate, specific errors, not Help me out.
14. The intermediate interface board (CORH0-1205B-V1.5-B) was inspected, connectors are clean.

Summary:

• LDS spins, sound output works.

• All motors are confirmed functional, mainboard tested.

• Most common error is Help me out. Sometimes LDS sensor is blocked appears but later clears on its own.

Question: What else can trigger Help me out in the OZMO 920 if motors, LDS, and the mainboard are excluded? Could it be related to feedback circuits (for example the suction fan with Hall sensor), or the intermediate board/ribbon cable?