Read only mode rootfs crash problem

[ricar]

Hello,
I have been using A20-Olinuxino LIME board, with Debian GNU/Linux 7.6 (wheezy) image booted from NAND. I mounted linux rootfs in read-only mode to avoid NAND corruption.
My board, during scheduled daily "shutdown -r", randomly crashes and I'm not able to connect using ssh. Using rsyslog I have this message before shutdown:

2016-01-03T23:00:01+02:00 VPL-PBX init: Switching to runlevel: 6
2016-01-03T23:00:01+02:00 VPL-PBX CRON[14745]: pam_unix(cron:session): session closed for user root
2016-01-03T23:00:03+02:00 VPL-PBX sshd[1613]: Received signal 15; terminating.

After this message I can't connect using ssh (connection refused) but it responds to ping. If I poweroff the board and restart it I get these rsyslog messages:
2016-01-01T00:00:08+02:00 VPL-PBX kernel: imklog 5.8.11, log source = /proc/kmsg started.
2016-01-01T00:00:08+02:00 VPL-PBX rsyslogd: [origin software="rsyslogd" swVersion="5.8.11" x-pid="1519" x-info="http://www.rsyslog.com"] start
2016-01-01T00:00:08+02:00 VPL-PBX kernel: [    0.000000] Booting Linux on physical CPU 0
2016-01-01T00:00:08+02:00 VPL-PBX kernel: [    0.000000] Initializing cgroup subsys cpuset
2016-01-01T00:00:08+02:00 VPL-PBX kernel: [    0.000000] Initializing cgroup subsys cpu
.........
I would like to know if read only  mode can cause a system crash during shutdown or during start of the operating system or what can cause this problem.
Thanks