“Operating system not found” Error on Windows 10

1) When running chkdsk switches on the windows drive typical behavior is for it to rise to a low number in the teens and remain there until the command has completed.

2) Chkdsk displayed results for C: (5/15/2019 7:38:40 PM)

Code:

Correcting errors in the Volume Bitmap.

Windows has made corrections to the file system.

3) What happened during error scan 1 and 2?

4) Run HD Sentinel: (free or trial version)
Hard Disk Sentinel - HDD health and temperature monitoring
Post images into the thread for results on these tabs:
a) Overview
b) Temperature
c) SMART

I am not sure what happened during those 2 scans. As I was looking at the progress it was stuck on the 13% for so long that I just looked at it periodically. I was thinking that it could run overnight but then when I checked back the computer had booted so I proceeded to run as many of the other diagnostics as I could. It is currently running the sea tool long generic now and when that has completed I will run the HD Sentinel you have suggested. Quite honestly I have been running so many diagnostics on it I cannot remember each of the occurrences and as I mentioned I was updating the windows on the other VAIO which I am using now to send you this reply. I am having problems still with the other laptop but I do not want to confuse anyone by referencing its issues in this thread since it has its own open thread.

There were two HD Tune full error scans.
One scan displayed errors and one scan displayed no errors.
What was done between the scans and how come there were two scans?

There was only 1 Error scan done in the HD Tunes. The reason there are 2 different images is because the second one is a speed map that measures the read performance across the drive -- at least that is what I read in the manual. The colors are not errors but are performance indicators so the green shows the highest performance, the yellow shows slower performance and the red shows the slowest performance. That options is chosen after the error log has run and once that test is complete you have the option of selecting the speed map. I believe I even named the file speed map or something like that so you would see the distinction. I apologize if that is confusing but I read it in the manual so I thought that was something you may have wanted to see -- I take it that must be a newer feature in that diagnostic tool since you are not familiar with it. The long generic test is still running on the Sea Tools and is at about 80%.

The speed map is a feature that we had never used/requested.

I am attaching the Sea Tools and HD Sentinel reports.

For HD Sentinel > post images into the thread (see post #11)

Code:

The drive tried to examine and reallocate data sector(s) 55 times. The examined data area is perfect.
    At this point, warranty replacement of the disk is not yet possible, only if the health drops further.
    Problems occurred between the communication of the disk and the host 70559 times.
    In case of sudden system crash, reboot, blue-screen-of-death, inaccessible file(s)/folder(s), it is recommended to verify data and power cables, connections - and if possible try different cables to prevent further problems.
    More information: https://www.hdsentinel.com/hard_disk_case_communication_error.php

Here are the images that I took of the HD Sentinel log.

The were problems reported by HD Tune and HD Sentinel for SMART.

S.M.A.R.T. Attribute: Reallocation Event Count | Knowledge Base

Some people replace a drive when there are predicted problems.
Others wait until drive failure.
Performance may be compromised.
And it may be unpredictable.

Make sure that you always have a backup image.

Run the Crucial scanner so you can view some replacement options: (SSD versus HD)

Crucial System Scanner | Crucial.com


Consider replacing the drive now as there were/are performance problems.

So it is most likely not a connection issue with the motherboard is what I am getting from your assessment and not just a common BIOS error consistent with this type of laptop?