"No current is flowing". The instrument is switched on and the displayed lightened up and a treatment is running but no current is felt:
This could be that the RCA plus is not properly pressed into the socket on the device.
The wire in one of the plugs may have become loose. Test with the tester.
Both the Wave4 and Wave5 use the same rechargeable battery (model 18650). They are freely available from shops that sell e-cigarettes/eVapes and LED flashlights.
The instrument is switched on and the display is illuminated but the screen appears to be frozen. A reset is then necessary.
To do this; one just have to open the lid on the back of the unit with a small screwdriver and with the screwdriver slide one of the battery's ends so that it will not make contact anymore. The screen will then go dead. Slide the battery back so that the battery make contact with the device again and the unit will reset again. Close the lid.
If the battery does not charge change the 5 volt 2 ampere charger with another one. If still not charging change the charging cable with another one.
Although the battery is suppose to only be replaced every 18th month, it could be in this case that the battery became faulty.
In this case just obtain another battery from a local shop that sells electronic goods