2009 Accord, 80k miles, was having some starting trouble. Took it to a shop, they checked alt/battery and confirmed alternator was bad. I ordered and installed a new Denso alternator. Negative battery cable was removed while I performed the install. I may have left it on during the removal.
After the install, I topped off the battery with my battery charger and started the car. I let it run for a good while, then drove it around few a few miles, then back home for the night.
Next morning (today), car won’t start. It turns over, but barely, very sluggish. I get the battery charger out again, and it’s telling me the battery doesn’t need much. I leave it on trickle charge for a bit. I try again, nothing, no turn over even. I try jump-starting it off another car, and nothing. No turn-over.
Now it really seems like the battery isn’t the problem, but just to be sure I go have it checked. It’s 100% A-OK.
So now I’m a bit stuck. New alternator, good battery, and a no-start condition. Electrical works: I can turn on lights and radio. But no engine turn-over, not even a click.