First-time flickerfixer users: look out!
we just solved an interesting support case, where a customer has added the Indivision AGA MK2 to his A4000D setup. He disconnected the power chord from the 15kHz monitor and used it for the TFT which is connected to Indivision. The 15kHz monitor was still connected to the Amiga, but not powered.
The Amiga would not start in that configuration. However, when the customer removed Indivision AGA MK2 and only used the 15kHz monitor, the computer would start. Since this looked like a problem of Indivision and the customer was close enough to my place for a saturday-afternoon-visit, we tested the unit here, and it worked perfectly.
Turned out that the Amiga has confused the powerless monitor with a Genlock. Upon power-up, the Amiga identifies a Genlock by the presence of Sync signals, and some monitors (for example the Microvitec standard monitor that Excom preferred) do exactly that: They let the Amiga believe that a Genlock is connected, and the Amiga crashes because of that (constant reset-loop).
If you are a first-time flickerfixer user and still have your 15kHz monitor connected as a backup, then it may keep your Amiga from starting if the 15kHz monitor is not switched on.