﻿ SOLUTION — Backwards Bomb

## Solution

The modules shown in the video provide enough information to deduce the complete edgework on the bomb.

### Batteries

• Murder implies that there is ≥ 1 D battery.
• Neutralization’s NaOH implies D ≤ AA, and therefore, ≥ 2 AA batteries.
• The Caesar Cipher offset can only be 1 or 2, but we already have at least 3 batteries. Therefore, we have 3 batteries (1 D + 2 AA) (and a vowel in the SN).

### Indicators

• Brush Strokes with Lime in the middle implies that the digits from Burglar Alarm must be 20 or 90. It can’t be 20 because we don’t have > 4 batteries. Therefore, it’s 90 and we have ≥ 1 lit indicator.
• Scripting has blue (top) false, so lit ≤ unlit, so we have ≥ 1 unlit indicator.

### Ports

• Murder implies that we have a serial port.
• Since we have only 5 widgets in total, we know at this point that they must be: 2 battery holders, 2 indicators and 1 port plate.
• Brush Strokes with Sky in the middle implies that the Safety Safe offset is 14. This can’t be from matching indicators because that would require 7+5+1+1 and therefore at least three indicators. Therefore, there are two port types.
• There is only one port plate, and it already has a serial port on it, so the other port must be a parallel port.

### Lit indicator

• can’t be TRN due to Murder;
• can’t be SIG due to Microcontroller;
• can’t be NSA due to Neutralization (3 batteries) or Caesar Cipher (parallel port);
• can’t be CAR, FRK, FRQ or IND due to Neutralization;
• can’t be CLR due to Text Field;
• can’t be SND due to Manometers;
• can’t be BOB because Scripting’s green (bottom-right) is false;
• therefore, it’s a lit MSA.

### Serial number

• In Connection Check, the battery-count rule applies, so we’re looking at the third character in the SN, which is always a digit. The red/green configuration shown only works for 7HPJ or 8CAKE.
• Microcontroller rules out an 8 in the SN, so SN character #3 is 7.
• In Battleship,
• the following information can be deduced without edgework: 4 0 ? ? ? ?
• A1 can’t be water because if it was, you couldn’t place the 1-ship anywhere.
• The ports/indicators/batteries give a radar spot of B5, which doesn’t help.
• Therefore, in order to produce a disambiguating radar location:
• one of the first two digits of the SN must be 4, 5, 9 or 0;
• one of the first two letters of the SN must be CEHJMORTWY.
• The Resistors have resistances of 66000 Ω and 330000 Ω.
• It can’t be in series because that would require 4 batteries.
• It can’t be the bottom resistor only for the same reason.
• If it’s the top resistor only, the first two digits in the SN are 66, which is ruled out by Battleship above.
• Therefore, it’s in parallel, the resistance is 1/(1/66000 + 1/330000) = 55000 Ω, so the digits are 55.
• The phrase “all resistance values are checked to be within 5% accuracy” from the Resistors manual does not apply as it refers only to checking the solution, not to how the module generates the puzzle. The module allows the answer to be off due to rounding, but it does not intentionally deviate the generated resistors when the result is exact, which in this case it is.
• Along with Connection Check, this means the SN starts with 557.
• Point of Order:
• Rule 1 (the suit rule) is violated, so rules 2 and 3 are in effect.
• Rule 2 implies that SN character #4 % 3 = 0, i.e., CFILRUX.
• Microcontroller rules out CLRX, which leaves FIU.
• Rule 3 implies SN character #5 % 3 = 2, i.e., BEHKNQTWZ.
• Scripting requires a letter from KTANE, which leaves EKNT.
• Battleship (see above) reduces this further to ET.
• Only Connect must have a unique answer for its first stage.
• What we already know: 2R Li TF HV Wa Ey ✓ ✓ ✗ ✗ ✓ ✓ ✓ ✓ ✗ ? ? ? ✗ ✓ ✗ ✗ ✓ ✗ 2 3 0 0, 1 2, 3 1, 2
• In order to have a unique answer, exactly one score must occur exactly once.
• Examining all 8 possible yes/no combinations for the unknown reveals there is only one possibility: no, no, yes.
• Therefore, SN character #4 is F or I, SN character #5 is T...
• Caesar Cipher requires a vowel in the SN, so SN character #4 is I.
• ...and SN character #6 is 3 or 5.
• In Ice Cream, Pat would be allergic to cookies if the SN ended in 4 or 5.
• Therefore, the serial number is 557TI3.

### Unlit indicator

• Scripting has bottom-left (red) true, which implies it’s SND, TRN, or CLR.
• Backgrounds has a 7, which can be AE, BA, CC, or FE. Out of these:
• FE is never possible;
• AE would require the button and backing to have the same color;
• CC would require 0 D batteries.
• Therefore, it’s BA. The button and the backing are not both primary colors, so the unlit indicator can’t be SND.
• It also can’t be TRN because we know from Brush Strokes with Sky (the Safety Safe offset) that the indicators have no letters in common with the serial number.
• Therefore, it’s an unlit CLR.

Finally, the clues below the video indicate how to piece together the solution word from the indicators and serial number. The digits are to be read as l33tspeak.

MISS SCARLETT