I get "High" on my Maha C9000 now and again. Always with old cells that are on the way out.
Charging even briefly on a dumb charger works but the cells get chucked before long.
The MH-C9000 features a high impedance tester which can screen for defective/damaged battery. Most consumer chargers on the market does not have this feature, and therefore will allow charging batteries not may no longer be suitable for use. Maha recommends that batteries triggering a "HIGH" error be disposed for safety reasons, as charging damaged batteries may result in overheating or explosions.However, if you feel the HIGH error is due to a false detection, try charging the battery first in another charger, or drain the battery first using the DISCHARGE mode on the MH-C9000. This is recommended only for advanced users.