Fix of DMTS_OAuthTokenRefreshFailedError in power bi/Power apps

Description

I need a freelancer with expertise in Power BI and Power Aps.
Short term issue:We have a data management solution with a custom powerapps App for data import relating to serialised inventory management and Work order ticket management.The data pulls through to a dashboard in Power BI however this has stopped refreshing giving us the following error:DMTS_OAuthTokenRefreshFailedErrorAll connections have been fixed in powerApps but error persists.error message detail suggest the issue is due to a token being inactive for 90 days but we do not know how to reinstate it.
Long term issue:Ongoing on demand support requirement for when things break as our original developer who created this system is no longer with us.1. The app used for data entry/scanning works but occasionally creates duplicate entries in the powerApps tables causing refresh failures - would like to get this fixed.2. Work order entries were automatically created in the app upon receipt of an email to a specific mail box. This worked when the format and sender of these emails was consistent. Both have now changed so this needs reconfiguring, and we need assistance importing historical tickets which have been processed manually into the system.