Hifi-remote.com has
this upgrade file which shows that the ADB 2721W uses the XMP IR protocol, device 42.20. Here's Power function 68
0000 006D 0000 0012 0008 0022 0008 0046 0008 0032 0008 006A 0008 0032 0008 0032 0008 0027 0008 0051 0008 020C 0008 0022 0008 0056 0008 0046 0008 0032 0008 0032 0008 0032 0008 001D 0008 001D 0008 0BEF
Ch+ (35)
0000 006D 0000 0012 0008 0022 0008 0046 0008 0032 0008 006A 0008 0032 0008 0032 0008 0027 0008 0051 0008 020C 0008 0022 0008 0065 0008 0046 0008 0032 0008 0027 0008 002C 0008 001D 0008 001D 0008 0BEF
You can assemble all of these using
IrScrutinizer with XMP-1 protocol
Power 68
num_0 81
num_1 15
num_2 1
num_3 2
num_4 3
num_5 4
num_6 5
num_7 6
num_8 7
num_9 8
CH+ 35
CH- 37
Last_ch 26
exit 7
Menu 33
Guide 36
Info 38
up_arrow 82
down_arrow 83
left_arrow 69
right_arrow 12
Select 84
Play 21
Pause 20
rewind 50
ffwd 53
Stop 51
Record 56
Back 64
Delete 24
On Demand 41
List 34
Red 66
Green 67
Yellow 48
Skip+ 22
Skip- 23
BTW, there's no reason to think that the box is a turd. However, I think we already know that most learning hardware doesn't handle modern IR protocols well....