CA FINAL-DT

can anybody help me to clear this below mentioned doubt.
suppose assessee not filed ROI u/s 139 and AO not done assessment under sec 143, 144

Then he issues notice
u/s 148 and asks him to furnish the ROI u/s 148
To proceed with assessment u/s 147

So my doubt is what happens if assessee don't file return u/s 148 or if he don't comply with that notice? How further proceedings against the assessee will be initiated...