Write these down, and confirm any guesses with the user:

Rails: the range of each rail while on (e.g. 5 V ± 5 %).
Power states:
- on;
- off with signals still connected;
- partly powered from another source (e.g. a module on USB with the main supply off);
- bench bring-up with parts missing;
- supply reversed.
Each connector pin: what normally drives or loads it (level, source impedance, frequency), and what can happen by mistake:
- a wire on the wrong terminal;
- a short to a supply;
- a hot-plug;
- ESD from a touch;
- a louder source than intended.
Misuse may stop the board working, but it must not damage anything.

2. Check each case

Take one power state or one misuse at a time, with everything else normal. Find the worst-case voltage at every IC pin, with tolerances at their worst corner. A coupling cap passes a sine unchanged, but a step can double the swing behind it.

Check	Pass when
Absolute max, every IC pin	Inside the rating, including relative to its own rails when they're at 0 V
Clamp diodes	Current through the series resistance stays under the injection rating. If the datasheet gives no rating, report that as a risk
Operating range	Inputs stay inside the common-mode range, and outputs don't clip at the levels the design assumes
Resistor power	V²/R at worst case, under the rating (0402 ≈ 0.063 W, 0603 ≈ 0.1 W, 0805 ≈ 0.125 W, 1206 ≈ 0.25 W unless stated)
Capacitor voltage	Under the rating. Electrolytics are never reverse-biased by more than ≈ 0.5 V
Ceramic DC bias	X5R/X7R run at no more than ~50 % of rated voltage, or the maker's bias curve shows enough capacitance
MOSFETs, switches	Vgs and Vds inside ratings, current under the limit, and the gate never floats
Output loads	At least the minimum load impedance, and current under the limit, including a shorted connector
ESD	Every exposed pin has a TVS or ESD diode at the connector, rated for the signal's swing
Floating inputs	Every input has a DC path to a defined level in every power state
Board interfaces	Each signal stays within what the other board's notes accept

If an assumed value decides a pass or fail, report the assumption itself as a finding.

3. Test plan and assembly faults

If the project has a bring-up plan (kicad-bringup):

Recompute each expected reading from the schematic, and propose a correction for any that changed.
Go through the likely assembly faults:
- bridges between adjacent pins of fine-pitch parts and connectors;
- a part missing, rotated, or the wrong value;
- a rail shorted to its neighbour.
For each fault, does it cause damage at first power, and would an unpowered reading in the plan catch it first? Propose readings for the damaging faults the plan misses.

4. Report

Findings, worst first. For each: what happens physically, in which case, the numbers and their sources, and a fix (or "accept, because ...") for the user to decide.
Passed checks, closest to their limits first, so the user can see the margins.
Design notes. Record only decisions the user accepted, with the reason. If a number in the notes is wrong, say so, and edit the notes only with the user's agreement.

kicad-design-review

Review a circuit by hand

1. State the environment