My '98 MT started and ran fine that morning. Stopped to get gas 15 minutes later and left the key in ignition. To my surprise it wouldn't even attempt to crank when turning the key. Did this several times with the same results. Turned on the headlights and they seem OK. Turned the key to ON and checked the voltage at 12.6. Battery was replaced a month ago. When turning from ON to start I noticed the fuel gauge go from F to 0 and I believe the other instrument
icons that had been on, went dim to off. After several more start attempts, it started right up (I have know idea why). Drove on in to work and noticed the
Fuel Range was "Low" then went to 39. Average MPG was 5 and had been about 20 earlier that morning. Clock time was also incorrect. When I got to work,
I popped the hood and check the battery. I could move the cable slightly by pushing with the most leverage on it. When I replaced the battery, I was cautioned about over tightening it. I then retighten it with several 45 deg turns, on both sides. Car has started fine next two times. Would a "not tight" but "not loose" battery cable caused this type of starting issue, or is there something else out there waiting to happen again.

DTC codes retrieved:
BCM: B0432H, B0503H, B0508H
LDCM: B2282H, B2284H, U1064H
RDCM: B2283H, B2285H, U1064H
SCM: B0851H