I have 2 V7 slim stick cleaners. One works as expected while the other shows the characteristics as indicated in my title. On normal mode it works fine but after switching to max power setting it cuts out after 2 seconds. At this point the sweeper is dead and will not work in either mode. I have to connect the charger for perhaps 5 seconds to get it to work in normal mode.  I think that the battery does not get emptied by going  to max power but something in the controlling circuitry calls a halt and the unit shuts down. I see no physical damage to the battery, contacts are clean. I was told there was a problem with the battery.  So paid £65 for a new battery and the fault is still there, So that was a waste of money.  Anyone else have the same issue?