Root cause for the issues of blank .info files and "system error ocurred" when attempting to do VA operations on AVX is manual reboot of AVX when it is coming up. The AVX had around 32 vAPVs, so avxd process hasn't finished starting all the VAs when manual reboot was done. Recommendation is a proper shutdown of VA and then reboot  AVX. 
Regarding issues seen due to manual disruption of power, blank .info file issue is already fixed in latest AVX build(Rel_AVX_2_7_5_10). 
Added two additional fixes:

1. Prevent “system reboot” command from executing in AVX when the VAs are still coming up. In AVX with 32 instances, it takes few minutes for the AVXD to complete initialization and for the VAs to come up fully. During this time "system reboot" will be prevented. I have not modified "system reboot noninteractive". 

VA could get corrupted when power chord is removed manually when AVX is coming up. After AVX comes up, this can result in continuous VA reboots as the VA is corrupted (could be empty /etc/fstab). This can make libvirt commands like “show va status” , “va start <vm>” unresponsive. To address this, made changes to shutdown VA if VA reboots 4 times in 3 minutes.

When avxd is still coming up:

system reboot

System is still coming up. Not safe to reboot now. Please try later

AN(config)#system reboot

System is still coming up. Not safe to reboot now. Please try later

After avxd comes up:
AN(config)#system reboot

All running VAs will be stopped and unsaved configurations on running VAs will be lost after this operation.

Please make sure that all VAs are shut down.

This will reboot the system immediately

type "YES" to continue:YES

Rebooting...

Added last reboot time and num of reboots to va.info:

 <hypervisor>0</hypervisor>

  <privatelicense>-1</privatelicense>

  <lastreboottime>1773228976</lastreboottime>

  <numreboots>1</numreboots>

</instance>