The black lead from the battery goes to the - connections between the yellow and red LEDs. (That was fine too)
J4 is the connector on the left side of the T1 control board.
J5 is the connector on the right side of the T1 control board.
Verify the MCU has no bent pins and is fully pressed all the way down in its IC socket. (OK)
Do you see 6V on pin 1 of the U1 processor when the PWR button is tapped? (use the thumbscrew or BNC jack for ground) (Yes)
You can test this at J4 pin 3, which is the pin just above and between the green and yellow LED, and it is the 3rd pin when counting beginning with the round pin 1 of J4. U1 pin 1 and J4 pin 3 are directly connected together. Remember that J4 is on the left side of the control board.
Also, J5 pin 3 should show 9V to ground when the unit is off and S1 has not been pressed. Remember, J5 is on the right side of the control board as you would normally face the unit. (OK)
When PWR button S1 is pressed and HELD down, J5 pin 3 should be 0VDC. (OK)
This change in voltage at J5 pin 3 and U1 pin 1 and the 6V appearing at U1 pin 1 must occur, or something is wrong with the power up circuit of D3, R7, C20, Q1, R14, S1, D4, C19, U2, D4. Check all of those parts and their soldering very closely. Both U2 (78L06) and Q1 (2N3906) should be installed with their flat side facing up. (Problem #1 Q1 was inserted backwards so chopped it out and replaced it with a new component the right way around this time)
Be sure D3 and D4 are not installed in reverse. D3's banded end goes toward R14, and D4's banded end goes toward switch S2. (Both OK)
MCU U1 must be installed with the notched end closest to the J3 remote 1/8" phone jack, or to the left as you face the main board. (Problem # 3 the uPC socket and uP were in reverse, so I flipped the uPC and T1 worked fine)
You can use an ohmmeter to check for any shorts between the connector pins and ground with the battery removed, and between any pins of the parts and a nearby connection that is not at ground. Note some connections are intentionally grounded. Use the schematic as a reference for these tests. You can find an accidental short circuit or solder bridge this way.
Examine both sides of both PCBs very closely using a bright light and a magnifier. Look for missed solder connections, shorts or solder bridges or splashes, etc. Remove any excess solder and clean up any poor connections as needed, using Soder Wik and a Q-Tip moistened with acetone or alcohol to clean the PCB. (The board was cleaned up a bit)
Do you ever see any LEDs light up when the PWR button is tapped (yellow LED), or if it is held down for more than 1 second (green LED)? (Operating as should now)
Did you verify the LEDs are not installed backwards? You can check them for correct orientation by using the diode test function on most DMMs. (Diodes fine)
First remove the 9V battery.
Then place the positive test probe on the anode connections for each LED at pins 1, 2, or 5 of the J5 connector, and the negative lead on the common cathode connection at either end of R9.
J5 is the connector on the right hand side of the tuner as you would normally face the top and front of the PCB (near R21). Pin 1 is the round pin near the battery compartment. R9 is near the left top edge of the T1 control board.
Each of the LEDs should light enough to be seen in a dimly lit room as you move the positive probe to J5 pin 1, 2, or 5 and hold the negative probe on R9.