Take the battery out of the retainer

Now that the tabs are bent to touch the motherboard contacts, place your retainer correctly oriented over the rom chip.

Heat your solder iron back up to temp and re-tin it's tip.

Gently press the retainer down against the rom chip and carefully solder the retainer's tab onto the battery contact on both sides.

If your retainer isn't fully touching the rom chip after soldering, you can press down and re-melt the solder joint to try to get the battery retainer to sit lower