Powershell - get console output into variable (not stdout, not stderror) - powershell

Question

I have the exe from Lenovo that only provides command line output when run from a cmd window but not from PowerShell. The output seems to come from a ghost source other than StdOut or StdErr.
https://download.lenovo.com/pccbbs/mobiles/n2hgc06w.exe (you have to run and click install but all that does is unzip to c:\drivers\win\touchpadfw). Be sure to cancel the install prompt after extract.
This command gives me output to the console
& cmd.exe /c c:\drivers\win\touchpadfw\touchpadfw_aug2019\synreflash.exe /v /S 2
This also gives me output the the console and nothing in the variable
$var = (& cmd.exe /c c:\drivers\win\touchpadfw\touchpadfw_aug2019\synreflash.exe /v /S 2) 2>&1
Same here
$var = (& cmd.exe /c c:\drivers\win\touchpadfw\touchpadfw_aug2019\synreflash.exe /v /S 2 2>&1)
I feel like this exe is outputting in some other way than StdOut and StdErr but I don't know what. Nothing I've tried can capture what it is outputting. Is there a third method of output?
This is where it gets weird. Using "start cmd" to open a cmd window from the admin PowerShell, I run the exe directly in the cmd window but the output goes to the parent powershell console. I cannot get any output if I start the cmd window as admin directly.

Answer 1

Look at the SynReflash usage below you will notice that you would need to pass the last arg as /S 3 explicitly, to print to Standard Output as opposed to /S 2 is a silent mode
$cmdOutput = cmd.exe /c "C:\DRIVERS\WIN\TouchpadFW\n2hgc06w\synreflash.exe" /v /S 3 '2>&1'
OR
proc = [System.Diagnostics.Process]::Start([System.Diagnostics.ProcessStartInfo]#
{
'FileName' = "cmd.exe"
'Arguments' = "/C " + """C:\DRIVERS\WIN\TouchpadFW\n2hgc06w\synreflash.exe"" /v /s 3"
'CreateNoWindow' = $true
'UseShellExecute' = $false
'RedirectStandardOutput' = $true # to get stdout to $proc.StandardOutput
'RedirectStandardError' = $true # to get stderr to $proc.StandardError
})
$output = $proc.StandardOutput
$error1 = $proc.StandardError
write-host $output.ReadToEnd()
Output
FW Version: 1.2