Piece of junk refers to something that is cheap, shoddy, or worthless. It can be used as an oject as in "This piece of junk won't boot." or a modiying adjective as in "This piece-of-junk computer won't boot" (with or without hyphens).
Related adjectives can be used with the name of the device. These include:
"Junky", "shoddy", "trashy", "lousy", "worthless", "crappy" (oh, and, of course, "shitty").
Boat Anchor which merely means the device is only suitable for that purpose. "This computer has become a boat anchor" (Urban Dictionary, definitions 2 and 3, Ham.net shows the term used in practice.)
Doorstop similar to "boat anchor". "This computer only works as a door stop now."
Junk Box No longer suitable for anything except to be cannibalized for spare parts. (See wikipedia.) Usually this refers to just the parts themselves, already disassembled and collected into a box. But it parallels your German reference, so I thought it was worth adding.
We also refer to some things as "hangar queens", which is alludes to aircraft that spend more time in repair than they do in service. Any products that can't get through the production process may be relegated to being hangar queens, with hopes that someone will eventually figure out how to repair them.