If you can't boot into CW recovery by holding power and vol+ for several seconds, you're pretty well fubarred. And at this point, I would guess you don't have a recovery system if the above step doesn't work.
If you have a pinhole for factory reset, it "might", and I say it loosely, might restore it back to factory.
Although flashing roms and recoveries are pretty normal nowdays, there are times when you miss just 1 small step, and off into bootloop hell. It happens. These are the risks we take.
If you're a tech knowledgable person, you might, and I say "might" be able to access the device via adb commands. You might possibly push a recovery. If adb can't communicate with the device, it's best to take it back to the service place, and say, it doesn't work.
But for your case, I would try to post at xda, android dev, for your tablet if it has a forum.