2007 Mitsubishi endeavor won't start

Hello, If the battery charger and tester said the battery is good, the alternator is likely not charging the battery. You can confirm this by testing the output of the alternator while the engine is running, or bringing the alternator to a parts store that checks them for free. If your alternator and battery are good, the battery cables and battery cable end terminals are the likely culprit, so those go up for testing as well (probably before the alternator). Your easiest option is to bring it in to a shop for a starting and charging systems check. Inexpensive, fast, reliable.