is there an escape for '&' character in the command prompt?
What you need to do is wrap your password in double quotes like so:
set pwd="abc&123"
echo %pwd%
Let me know how it goes.
I found that it works best with a combination of both martineau's answer and mastashake57's answer.
set pwd=abc^&123
echo %pwd%
Still fails, and
set pwd="abc&123"
echo %pwd%
Adds quotes to it (you can't remove the quotes with a for loop or string manipultaion because it will fail again, thanks to the ampersand), which isn't that great.
However,
set "pwd=abc^&123"
echo %pwd%
Works perfectly.
Hope that helps.