1. Is it so important that I should be using that expensive Fulke multimeter coz mine is not that costly so not as much quality.
Of course not, the multimeter does not have to be expensive,anything that has the functions needed will do the job, here , this guy uses a different multimeter >
https://www.youtube.com/watch?v=CKlMciBvb8A2. What else I can do to detect the bad chip?
Non that I know of , aside from using the fixture or testing each and every chip.
3. Text fixture(as far as I saw on videos) also shows like found/has XX(Number) Asic like in Kernel log, is not it? So really if kernel shows 10 asic on a hashboard, could it be the 50th chip? Will Fixture device show that its not 10/11 but 50th chip?
I am "almost" certain that the log won't detect the exact chip , first of all , if it does , then how do you explain most chips show 0 asic or 57 asics, I have never had a kernel log reading 44asics, 15 asics it's always the same sets of numbers, also if the kernel log was to give you this, then nobody would have made that fixture tool , in fact even "S9 Repair guide manual" mentions something related to using the fixture and multiplier.
4.(The Most Important) Can you say that It will %100 show an abnormal value on either resistance or voltage values if I check every single chips' test points on a hashboard? Coz I have time and ambition to do that sir.
After reading the "S9 Repair guide manual" I am 100% certain that a bad chip will show abnormal values IF tested correctly.
I came across the "S9 Repair guide manual" after visiting that
Chinese Youtuber's website in an attempt to make a bit of research for you on this subject, I found that on his website he has a link to a PDF file which is the "S9 Repair guide manual[EN]" seems like it came from Bitmain, that PDF file has almost every single tiny detail about troubleshooting Antminer S9 , after all this time , I am surprised that I haven't came across it, anyhow you should read it , it has all the answers you need.
keep in mind that his website has 1/71 on Virustotal , which means that one engine out of 72 detected this URLas Malware which I think is false positive, but be careful and visit it at your own risk.