It would help a great deal if you posted the exact error you get.

I put in a print statement after the variable assignment to $prompt,

print "$prompt\n";
[download]

and got this result:

ash-2.03\\
[download]

Hence, I think you need to change your strategy on the second line.

Also, (guessing here) I don't think you want to set that prompt in the "new Net::Telnet" object creation. You should just leave that out if you're going to use the explicit open & waitfor strategy.