I had a new battery put in my 1997 Nissan Maxima.

Fuse beside battery terminals check called a fuseable link

Here is a list of radio wiring harness wire color codes and what they do. I have given both with and W/O Bose.

Nissan Maxima Car Stereo Radio Wiring Diagram Radio Constant 12V+ Wire: Pink/Blue
Radio Ignition Switched 12V+ Wire: Blue/Black
Radio Ground Wire: Vehicle Chassis
Radio Illumination Wire: Red/Blue
Radio Dimmer Wire: Red/Orange
Radio Antenna Trigger Wire: Black/Red
Front Speakers Location: Doors
Left Front Speaker Wire (+): Blue/White
Left Front Speaker Wire (-): Blue/Yellow
Right Front Speaker Wire (+): Brown
Right Front Speaker Wire (-): Brown/White
Rear Speakers Location: Rear Deck
Left Rear Speaker Wire (+): Red
Left Rear Speaker Wire (-): Green
Right Rear Speaker Wire (+): Blue
Right Rear Speaker Wire (-): Pink
1997 Nissan Maxima with Bose Stereo Wiring Diagram W/Bose
Car Radio Battery Constant 12v+ Wire: Pink/Blue
Car Radio Accessory Switched 12v+ Wire: Blue
Car Radio Ground Wire: Chassis
Car Radio Illumination Wire: Red/Blue
Car Stereo Dimmer Wire: Red/Yellow
Car Stereo Antenna Trigger Wire: Black/Red
Car Stereo Amp Trigger Wire: Green/White
Car Stereo Amplifier Location: Each speaker has its own amplifier located at each speaker.
Left Front Speaker Positive Wire (+): Yellow
Left Front Speaker Negative Wire (-): Brown
Right Front Speaker Positive Wire (+): Violet
Right Front Speaker Negative Wire (-): Light Green
Left Rear Speaker Positive Wire (+): Red
Left Rear Speaker Negative Wire (-): Green
Right Rear Speaker Positive Wire (+): Pink
Right Rear Speaker Negative Wire (-): Blue

Hi,

If this is still the factory head unit then you need to reenter the security code so that it will operate again.
As for the clock, you may have a faulty connector or blown back light bulb. The clock maybe working but you cant see it as the backlighting is not working.

Thanks

Jason

Yes it is a fuse

More than 1 fuse on that car can power the clock. Check all the fuses and replace any bad ones.

just push up on the clock part you wont break it, the pull down once it pops. unplug defroster and clock and caution lights.then put the car in 1st gear and pull up the trim around the shifter, unhook the cig lighter then unscrew the ash tray and unplug the light. then there should 4 more screws two on top two on bottom. and there you go

Check the mechanical condition of the battery cables; I have seen cables more than once that appeared OK but battery acid had crept under the plastic insulation and dissolved the copper inside.
I confess that this normally shows up first with hard starting or noticeable dimming of the headlights when other accessories are turned on but you have done the other things I would have checked already so it's time to check the cables coming off the battery at both ends. 

You do need an alternator. Nissan has a campaign on Maxima alternator in certain years such as 96-98 I believe. Go to your friendly Nissan dealer abd have them punch your VIN number into the NNA net. they will know and that will tell them if your vehicle applies by the VIN. I have seen the alternator on fire. There was fire inside of the alternator. Have it checked or the car can catch on fire.

You have a blown fuse for the memory for the radio & the clock.

Check all of your fuses