Garmin ECHOmap 92sv repair questions

[billtsig]

Hi everyone!

recently a friend gave me the marine gps (garmin echomap92sv) to be more specific my friend went the gps to garmin service but they said that it needs a new motherboard and it can't be fixed

so he bought a new one and game me the defective one and told me "keep it and if you can fix it it's yours"

at first i plug it to my bench psu with 12v and the device consumed about 50mA and every 1 sec about 100mA (as a pulse) later it turned on it's self and was fully functional for about an hour until it stopped working again

after that i took some  measurements to all the smps rails and the voltages was present without short circuits

the only abnormality i found was at the multi smps chip (let me call it multi chip) that none of the voltages was present and on one of it's coils a short pulse every 1 sec 0-5V was here

there was no short circuit either, sadly i didn't manage to get a datasheet for the chip (sn140502 texas instrument) or a garmin service manual   

im thinking that the control chip still see an error and does not the smps let to start but i can't identify the error
pcb images:
https://freeimage.host/i/dMLnnDP
https://freeimage.host/i/dMLnCOB
https://freeimage.host/i/dMLnqHQ
https://freeimage.host/i/dMLnKUx
i would be very happy if anyone could help me with directions to repair it because i own a small boat and it would be much better than my android phone im currently  using now as a gps

thanks for your time

Vasilios