The intended audience for this document are people with a technical background.
When a previously running Mpowered installation fails, this is due to a system problem. In general, system problems always happen because some sort of change was introduced; whether the change is configuration, database or environment; intentional or unintentional; major or minor. The long and short of this is that if nothing had changed, your system would still be running!
Your Mpowered specialist left you with a working system, and it continued to work for some time, and now it is not working. A typical trouble call goes, "My system was working perfectly yesterday, and now xyz is happening." This is always indicative that a change happened between yesterday and now. It is tracking down that change and rectifying the problem the change caused which can sometimes be difficult. A seemingly minor or even seemingly unrelated change can cause the system to fail.
In order to mitigate "urgent" trouble calls, it is highly recommended practice to first run any proposed changes to the live system through a test system and doing full end-to-end testing before committing those change to the live system. However, time crunches and other factors occasionally do not allow this recommended way of introducing change. By walking through the following checklist of questions and determining if any changes have happened, you can generally either rectify the problem, or reverse the change that caused the problem.