BBB with cape 7inch LCD faulty screen

I have built a new host from debian-8.6.0-amd64-CD-1.iso and included eclipse mars.2 with debugging for bone-debian-8.4-lxqt-4gb-armhf-2016-05-13-4gb.img.xz installed on a BBB with a 7 inch LCD cape.
At the beginning of uEnv.txt I included as a first line:
dtb=am335x-boneblack-emmc-overlay.dtb
For file capemgr:
root@beaglebone:/etc/default# nano capemgr
GNU nano 2.2.6 File: capemgr

Default settings for capemgr. This file is sourced by /bin/sh from

/etc/init.d/capemgr.sh

Options to pass to capemgr

CAPE=BB-BONE-LCD7-01:00A3
I added the above last line: CAPE=BB-BONE-LCD7-01:00A3
root@beaglebone:/# cat /sys/devices/platform/bone_capemgr/slots
0: PF---- -1
1: PF---- -1
2: PF---- -1
3: PF---- -1
4: P-O-L- 0 Override Board Name,00A3,Override Manuf,BB-BONE-LCD7-01
Which I believe means the cape is loaded.
The above is working satisfactorily except the display is very faint. I can turn on the backlight with:
Manually:
root@beaglebone:~# echo 1 > /sys/class/backlight/backlight/bl_power
Or:
echo 1 | sudo tee /sys/class/backlight/backlight/bl_power
Placed in .bashrc
These turned the backlight on but seemed to cause some mouse and screen instability. If I don’t do this everything is stable but so faint that the display is almost unreadable.
This is a first attempt by me. Any comments or improvements would be much appreciated.
Many thanks,
Kevin.

What is the best method to automatically ensure that the display backlight is on after boot? Initially the screen is white then switches to faint graphics (backlight off). Thank you! Kevin.