A word of caution to the 20 die-hard Gorillaz fans who have held on since the “cartoon band” debuted four years ago: Blur’s Damon Albarn is the only contributor to return for Demon Days. The same fictional characters fill the liner notes, but every real-life musician has been replaced, with DJ Danger Mouse of The Grey Album taking on the unfortunate task of following Dan the Automator as mastermind and producer. At least he got two songs right: the stuttering organ, slow beat and hard-edged rap by Pharcyde’s Booty Brown on “Dirty Harry” create a catchy answer to the last album’s dub-smash “Clint Eastwood,” and “Feel Good Inc” stands out because it’s the only track on Demon that steps out of the Automator’s shadow. A few other songs have catchy moments, and Albarn again proves his vocal versatility, but Danger Mouse wastes too much time trying (and failing) to copy the punk- and rock-influenced hip-hop style of the debut. As a result, the humor and fun of Gorillaz have been wrung dry. Add the two singles to your computer play list and leave the rest of Demon on iTunes.