Regarding the current measurement: Did you have the current routed through the A and C ports of the Mooshimeter? If so, can you check if the fuse is blown? If the fuse is OK, there will be continuity between the A and C ports on the Mooshimeter. If the fuse is blown, there will be an open circuit between the A and C ports.
Connecting and seeing “Status: -1”: I assume this in on Android? -1 is a timeout, and in my experience this is an issue on the phone side. It can usually be resolved by turning bluetooth off and on again on the phone before trying to reconnect, or rebooting the phone.
Measuring resistance: the behavior you’re getting sounds wrong, it shouldn’t be jumping around like that. Please email me at email@example.com if you’d like to talk about replacement.