I’ve got the LoRaWAN plug and play for helium network and am unable to view/edit the app key in configuration mode. Dev/EUI are both visible and changeable, but App key is all Xs and I cannot edit/change anything.
Welcome in club, same here for TTN ! Documentation form third parties for that fw is missing some fundamentals part 
This Wio LoRaWAN FieldTester is a plug-and-play and all-in-one LongFi network monitor for Helium network. It will help you particularly know how many Hotspots around can be touched for a given position, enrich the network mappers to know each other and share the real network coverage.
You can also apply it here for amazing and remarkable performence.