But debugging the hardware is another story.
What I propose here is a debug version of EmuTOS. It will boot and display progress messages. So you will know where it hangs. We already used that technique to debug the FireBee and other stuff, and it has proven to be easy (well, easier than anything else). One of the main features of EmuTOS is support for non-Atari hardware. More precisely, it is possible to selectively disable the usage of hardware components such as YM-2149, ACIAs, etc. So if you suspect some component to have trouble, just disable it, and see if it goes further.
EmuTOS is very versatile, it can be built as 192k ROM or 128k cartridge (and many others variants). Just tell me what form is best for you, and I will build it. Debug information can be sent to screen or serial port, as you wish.
Those settings needs do be decided at compile time, so please tell me your needs first.
I will be glad to help you to go forward.
PS: Of course, when hardware is debugged, you can go back to TOS
