I'm having the same problem with an iPod touch 4G. Tried wall charge, computer charge, cable changes, no avail. All I had done was applied a new Stealth Guard to the screen, involving getting screen wet.

With no cables it won't respond, so assuming sucked up all baterry completely. When connected I get the thin red line and the thunderbolt sign, but never gets past that despite connected several hours. iTunes only detects it if I get it onto recovery mode. Jailbroken and all, would prefer not restoring. Is that truly my only chance. Looking for similar threads, still not an answer..