RepairPal Certified shops can diagnose and repair your 2007 Isuzu Ascender. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
On page 507 in the owners manual you'll find information about the fuse box under the rear seat .. Within that fuse box is a fuse for the stereo amplifier .. IF that isn't the problem - seek hands-on help from qualified personnel.