Installing new chips

[Kevin <kevin@minds-eye.org>]

I thought I'd run this by the list,

I tried to install an upgrade chip in a Digitech 2112 (to a 2120) and am 
now facing a unit that has no output.  The meters show an input signal, 
but no sound emerges.  I've installed chips
successfully in other Digitech gear so I expected this would be no 
problem.  Guess not.

Anyone know anything about this upgrade or perhaps universal upgrade 
techniques that may be applicable?

Thanks for any help

Kevin (feeling very much the blunderer)