This may sound like a dumb question, but did you download the Archim Dual Endstop firmware?
Second question, are you sure the flash was successful (the previous times) What version does it say on your LCD (if you have one)? It should say something like 425 D. (I am not certain what the latest version is, but most importantly the D indicates its dual end-stop firmware)
You say your screen is blank, I am going to assume you mean an LCD you have hooked up to the Archim. You also say you get an error now, but its unclear when you get this error, or where, or what the error is exactly.
As @rwillett said, you need more information if you want help.
To be clear, I have the Archim 1, with Dual End stops, and have gone through my fair share of debugging getting it to work, so I might have an idea what is going wrong with yours; but not without more detail.