Unless the dust in your SE is electrically conductive (unlikely), its principal effects are going to be in inhibiting cooling and in shortcircuiting traces/pins when wetted (which should be seldom). Dust is extremely unlikely to produce SadMac codes relating to software hiatus or to physical breakdown of RAM.
A reference to your original post would have been handy, because much of the discussion there is still pertinent. Mac error codes can be instructive, but they can also be the first explanation that a Mac puts forward to explain its ingratitude about being revived. It is not far enough into the boot sequence to have a System loading, and it is in the awkward position of having to diagnose its breakdown while it is yet barely sentient, or even still comatose. In short, it puts out the first porky that comes to 'mind'.
Ignore the FDD for the moment, but disconnect it from the MLB to avoid untoward effects. Use the Centris to format and install your desired System onto the HDD intended for the SE in an external enclosure. Depending on the System chosen you may be able to choose a System 'for any Macintosh' or for a 68000 Mac, but don't choose 'for this Mac' because that will be the Centris. Make the insides of the SE spotless, reseat anything that can be reseated after inspecting and cleaning the connectors, and see whether you can boot from the known-good HDD with a fresh installation of a System. (Simply spinning up is not proof of a drive's goodness.) If the System is 68000-compatible, you should not get a software error. If you get the complaint about the RAM again, there may be some substance in it, and you can respond accordingly.
Inspection of the MLB will reveal only gross faults. Many faults in traces can be inaccessible to inspection, but usually result only from extreme abuse of the MLB or attack by capacitor goo, which is itself not hard to see. Systematic test and procedure will get you a working SE, given no catastrophic defect such as chip failure, but you need to be prepared for the slog towards destination.
Canned air is canned air. It should contain only air (or nitrogen) and a harmless propellant. Its principal virtues are that it is clean and carries no chip-killing static charge (as a vacuum-cleaner on 'blow' rather than 'suck' would do).
de
A reference to your original post would have been handy, because much of the discussion there is still pertinent. Mac error codes can be instructive, but they can also be the first explanation that a Mac puts forward to explain its ingratitude about being revived. It is not far enough into the boot sequence to have a System loading, and it is in the awkward position of having to diagnose its breakdown while it is yet barely sentient, or even still comatose. In short, it puts out the first porky that comes to 'mind'.
Ignore the FDD for the moment, but disconnect it from the MLB to avoid untoward effects. Use the Centris to format and install your desired System onto the HDD intended for the SE in an external enclosure. Depending on the System chosen you may be able to choose a System 'for any Macintosh' or for a 68000 Mac, but don't choose 'for this Mac' because that will be the Centris. Make the insides of the SE spotless, reseat anything that can be reseated after inspecting and cleaning the connectors, and see whether you can boot from the known-good HDD with a fresh installation of a System. (Simply spinning up is not proof of a drive's goodness.) If the System is 68000-compatible, you should not get a software error. If you get the complaint about the RAM again, there may be some substance in it, and you can respond accordingly.
Inspection of the MLB will reveal only gross faults. Many faults in traces can be inaccessible to inspection, but usually result only from extreme abuse of the MLB or attack by capacitor goo, which is itself not hard to see. Systematic test and procedure will get you a working SE, given no catastrophic defect such as chip failure, but you need to be prepared for the slog towards destination.
Canned air is canned air. It should contain only air (or nitrogen) and a harmless propellant. Its principal virtues are that it is clean and carries no chip-killing static charge (as a vacuum-cleaner on 'blow' rather than 'suck' would do).
de