Help No sim card error without sim card, no IMEI

[jga2z]

I just got a used AT&T HTC Vivid with what turns out are 2 anomalies that I failed to observe initially.
First I tried to put my ST sim card out my AT&T SGS, and get no service. No big shock initially since I have to change the APN info. Couldn't do that cause option is dimmed.Checked further, unknown IMEI, IMEI SV, no baseband. Took sim out and observed that I get NO sim error at startup, just "no service". Tried an AT&T sim from a friends Vivid, same result.
I was hoping that the sim card reader just might be bad, a cheap easy fix and apparently some what of a common issue. Haven't ordered one yet until I get more info on whether the no sim error and no IMEI etc are related and it's not a more serious hardware issue.
I don't think (but don't know 4 sure) that this phone is anything other than an out of the box stock configuration. I don't have service with AT&T so I don't know how much help they would be. I did check with them to make sure IMEI printed on the phone wasn't blacklisted and it's OK. All I have done was to do a factory reset to clear all the PO's stuff.
I don't have a problem with repairing hardware if needed.I'm a noob here, but have a brain like a sponge, so any thoughts on how to proceed with diagnostics would be appreciated. Thanks in advance

 

[jga2z]

Can I root or unlock this phone without a sim card or current service carrier?
Also is unlocking bootloader the same as unlocking to use on another GSM carrier (not AT&T)?

 

[jga2z]

Not sure anybody will read this or have any info but here goes.
Well I finally got a new SIM/SD card reader and installed it. No change.Tried ST, AT&T, and T-mobile sims
Still get no SIM error when booting with or without a SIM card, has an X on signal strength, and it doesn't even say "no service".
Same as to IMEI etc. info, nothing shows up.
Am I going to have to change mainboard? Or is it possible firmware/ROM changes could fix it?